Updates for MOS and Console8

I've been working to update Vezza across multiple platforms over the past few months, and now it's Agon's turn. It's recommended to update for anyone using Quark VDP 1.04 or above, or Console8.

Vezza has  been updated in a number of ways including:

• Code optimization for faster execution in some cases.
• Fixed the codes used to turn the cursor on and off. This means that redraws on large text screens are nice and clean. e.g. playing `rogue.z5` no longer has the cursor following the redraw.
• Added the new quit from terminal mode feature available in the Console8 VDP 2.2.1 and above. On Quark VDP and other versions the code is simply ignored and you still require a reset to exit.
• Fixed some error messages that were incorrectly swapped out for general messages.