History of TaskShell

1.00 - Handled basic screen I/O and keyboard. Special keys were hardwired to
       generate codes which were compatible with an ancient version of
	   LineEditor and programs using my version of the UnixLib termcap file.
	   Therefore, many things did not work.

1.10 - Re-wrote the keyboard handling code. Now emulates OS_Byte calls
       221-228. This means that recent versions of LineEditor now work.

1.20 - Re-wrote the screen handling code. Previously, it used OS_Byte 3 to
       disable the screen when inside Wimp_Poll. The code then trapped all
	   OS_Byte 3 calls and vetted them to ensure that no other program
	   enabled the screen. This was not a foolproof method of handling
	   things. The new version does away with all that messing about and
	   gets right down to the OS_WriteC vector. This should be foolproof.

1.21 - At the suggestion of Julian Wright, I re-wrote the startup code.
       Previously, it assumed that you wanted to go into mode 0 when
	   entering the TaskShell command line. This is not what most of you
	   lucky, lucky people with better machines want. TaskShell now starts
	   in the same manner as ShellCli, i.e. it scrolls the desktop. I have
	   added the ability to run a command from the TaskShell command line.
	   So, to emulate the old behaviour, you can do 
	   TaskShell "echo <22><0>"
	   RISC PC users can presumably do something similar to select their
	   favourite text mode.
