History:
v1.10	 	2nd February 2003
		Added command-line interface for use with DirSync.   If program is called with -noicon option it will then expect the names of the two files to compare to be supplied as the following options on the command-line, e.g. "Run <SideDiff$Dir>.!Run -noicon IDEFS::4.$.temp.Ch07 IDEFS::4.$.Text.Documents.B7.NotToKnow.Textfiles.Ch07"
		If run under the -noicon option, SideDiff will display no iconbar icon and will quit as soon as its main window is closed.   If -noicon is not specified, any further command-line arguments will be ignored and the program will start up on the iconbar as normal.
		Window no longer resizes to maximum when you drag in files to one or the other pane - the annoyance value of not being able to see the full pathname is far less than that of obscuring the Filer window you were about to use for the next file!
v1.11	 	26th March 2003
		Altered !Run file to default to using Internal copies - otherwise it's just too confusing for new users, who expect the program simply to work first time.
		Allowed -noicon option to take only one filename parameter. If only one filename is supplied, this is expected to be the name of an existing diff file (for use with CVS)
v1.12	 	30th March 2003
		Fixed window redraw on later WIMPs

v2.00	 	(24th May 2003) **MASSIVE UPDATE AND BUGFIX**
		Improved standard display.   Filenames are now held in right-aligned icons above the display panes, so that the leafname is always visible.  Window no longer pops to the front, obscuring Filer windows, whenever a file is dragged into it.   Massive changes to redraw code should provide faster horizontal scrolling and eliminate virtually all flickering.
		Implemented 'landscape' display mode for Jeremy C.B.Nicoll - the two panes are displayed one above the other, giving a wider potential display at the loss of some other features.
		Implemented editing facilities, by popular request.   Sections can now be selected with the mouse and copied from one file into the other by clicking on the new 'transfer icon', selectively eliminating existing differences.  This requires a third GNU utility, 'patch', which has thus been added to the Resources directory.   Also implemented editing of BASIC files via a slightly different mechanism.
		Implemented line numbers, by popular request.   The line numbers column may be removed altogether or dragged to a configurable width.
		Removed support for configuration via system variables in !Run file, and added an extensive range of configuration options in a new Choices window, which can be saved permanently to file.   This includes redefining all colours used in the display panes.
		The 'diffs' generated when files are dragged into SideDiff can now be saved out for later use or inspection.
		The paths for each of the GNU utilities are now set individually, instead of in a list via SideDiff$Internal/External.
		Major changes to menus to conform with Castle's new guidelines.Set up various 'info' system variables (SideDiff$Title, SideDiff$Running, etc.)
		Multiple copies no longer overwrite/delete one another's scrap files.
		Improved handling of 'softwrapped' paragraphs (paragraphs consisting of a single long line like the ones in this file!)   Sections from the middle of these are no longer falsely displayed as lines common to both files.
		Removed support for passing command lines without DDEUtils.   SideDiff now *requires* DDEUtils (if you don't own the module, you'll have to get a copy of one of the freeware clones).
		Got rid of bug where attempting to enlarge a window at maximum size instead caused it to progress leftward across the screen - toggle size also now works as expected.
		Improved percentage display - no longer gets stuck and then 'jumps' over large chunks.
v2.01	26th May 2003
		Changing display mode when an error message was displayed could cause a crash - fixed.
		SideDiff ignored a configured landscape display on start-up - fixed.
		Control characters in input could produce weird display effects - added machine code filter routine to check all strings before displaying them.
		It is no longer possible to save out a 'diff' if the comparison has failed.
		Yet more changes to try to avoid panes going funny under extreme conditions.
v2.10	13th October 2003
		No longer requires new SharedCLibrary to be loaded
		No longer requires bascat utility - SideDiff now does its own detokenisation
		'Refresh' menu entry will force the window to be updated with a fresh comparison between the files currently being displayed (i.e. if they have been edited by some other means since the last diff was taken)
		Preserves scroll offsets after a patch or refresh operation -  no need to scroll back to previous position
		Shift-clicking on a line of text in either pane will open a throwback window displaying just that line, which can be used as a quick & nasty way of opening the relevant file at that line
		Context header regexps (defining what is considered to be a start-of-section line when generating the context header display) are now enclosed with quotes before being passed to the command line, allowing a wider range of regexps to be used without causing errors.
v2.11	7th November 2003
		When BASIC files are being compared, 'Refresh' now reloads *original* files rather than detokenised versions in !Scrap (since the BASIC copies are the files displayed by the Shift-click throwback mechanism, and the only ones the user is likely to be altering using another application!)   Note that this means any changes made in the interim by saving 'patched' versions out as BASICtxt will be forgotten.
		'Auto' width of line number display now takes into account the current desktop font width on RISC OS 3.5+
v2.20	13th March 2004
		Ctrl-L now correctly toggles the 'Link scrollbars' option again, instead of triggering a refresh.
		Implemented the ability to scroll up/down to the start of the next chunk or the next altered line.
		Added toolbar to allow mouse control of this.
		Added new Compare window which appears when files are dragged to the iconbar, to allow the user to select which files to compare without the desktop's being obscured when the main display pops up.
		Throwback now works even when 'normal' editing is disabled.
		Moved save/cancel/set icons to right-hand side of Choices window, by request, and removed visible pane border.
		The 'Save diff' menu option is now greyed out when an existing diff file is loaded from disc (rather than offering to 'save' what would be the results of the previous diff!)
		The 'Refresh' menu option is now greyed out when the files referenced by the diff file being displayed no longer exist (rather than giving an error and blanking the window)
		Added "show whole file" option, which overrides and hence greys out the 'lines of context' options.
		Key shortcuts:   Ctrl-PageUp/PageDown - go to next/previous chunk, Space - go to next altered line, Hyphen - go to previous altered line, Ctrl-T - reopen floating toolbar, F3 - save out diff file, F1 - open help file
		Pressing TAB to toggle input focus between the panes now works even if 'Link scrollbars' is selected.
		Now uses a cream background for the slider above the pane with the input focus, providing a visible cue as to which is currently selected.
		Added 'Discard data' menu option to allow the user to reclaim memory after creating/displaying a large diff file.
		ADJUST-click on iconbar now opens Choices window.
		Toggling between the two sections of the Choices window no longer causes the window to lose the input focus.
		Fixed bug in machine code when detokenising GOTO lines
		Hardwrapped Help file to 78 columns to make it compatible with Web browsers (a deplorably retrograde step!)
		ADJUST-clicking on close icon now opens parent directory of pane with input focus (rather than always using the left-hand pane)
		Removes iconised windows from Pinboard before reopening them
		Increased Wimpslot by 4k
v2.30	18th July 2004
		Added outline font capability.  Display submenu allows font name, size (x and y res) and height (y res only) to be selected, plus new section with preview icon in Choices window allowing default font setup to be saved
		Added support for copying data out to global clipboard
		Added Selection submenu with key shortcuts
		Fixed bug where ADJUST-click on close icon caused crash if SideDiff window did not have input focus
		Moved hard-coded Compare window title (created from within program) out into Messages file to allow for translation if desired
		Added extra Choices... menu entry to main window menu when SideDiff is invoked with '-noicon' option (e.g. from within DirSync program). This allows access to regexp options, etc.
		Fixed bug where saved window background colour configuration was ignored in favour of default grey
		Choices window now restores input focus when closed
		Increased Wimpslot again