Externalised game text strings to a configuration file: GAME.HOV.
Added ability to specify the warp screen colors via the GAME.HOV configuration file.
Removed hard coded game text strings due to memory constraints (GAME.HOV is required in order for the game to run now).

Added ability to play new sounds.
New sounds are mapped to sound playing events externally with an optional configuration file: SOUNDLNK.HOV.
The default hard coded mapping emulates the original sound mapping.

Added enemy counter and total for display at the end of each level.