Fixed code size overflow crash

Adding the new keyboard code in the last release pushed the code
size beyond the 4K region allocated for it. The colour/mono
functions were then corrupted by the stack or overwritten by the
look-up tables generated at B000.

The look-up tables have been moved to B200, to give an extra 512
bytes of space. The stack has also been moved to hang back from
C000, which is after the end of the look-up tables.

Also changed the green ghost to dark yellow, to be closer to its
original orange colour. Changing the maze colour also uses the
bright version unless Shift is pressed.

ReadMe.txt

@@ -1,7 +1,7 @@
-Pac-Man Emulator for Sinclair Spectrum (v1.4)
+Pac-Man Emulator for Sinclair Spectrum (v1.5)
 ---------------------------------------------
 
-This program requires a Spectrum +2A/+3, and will not work on earlier models.
+This program requires a Spectrum +2A/+2B/+3, and won't work on earlier models.
 
 The Pac-Man ROMs cannot be supplied with this program, so you must supply your
 own copies of the following files (from the Midway ROM set):
@@ -14,12 +14,33 @@ or combine manually using:
 
   cat start.part pacman.6[efhj] end.part > pacemuzx.tap
 
+Then load the .tap tape image in a Spectrum emulator of your choosing.
+
+Controls:
+
+  1 = 1 player start
+  2 = 2 player start
+  3 = insert coin
+
+  C = colour sprites
+  M = mono sprites
+  H = hard difficulty (hold during ROM boot)
+
+  Cursor keys, Q/A/O/P, Kempston/Sinclair joysticks = joystick control
+
+  Sym-1 to Sym-7 = set display colour, add Shift for bright
+
 Many thanks to #zx and WOS for feedback and testing :)
 
 Enjoy!
 
 ---
 
+Version 1.5 (2016/11/19)
+- Fixed code overflow crash on mono/colour toggle (thanks Matthew Logue)
+- Changed maze colours to be bright by default, with Shift to dim
+- Changed green ghost to non-bright yellow, to be closer to orange original
+
 Version 1.4 (2014/03/01)
 - Added support for diagonal control inputs from keyboard and 8-way joysticks