Some fixes to the map attribute display
Add game description files for Scubaventure
Correctly import tilesets containing variable-width tiles
Handle layers where the tile image dimensions are different to the cell sizes
Monster Bash: Add sprites and other files
Halloween Harry: B800 format type consistency
Remove duplicate comments
Rename supptype item type flags to allow more specific tilesets to be given
Break out the palette as a separate file/resource type
Don't crash when opening map attributes and there aren't any
Better handle multiple tilesets and prepare for multi-layer map selections
Correctly save altered instrument in music editor
Replace SDL with PortAudio
Finalise MIDI timing

MIDI playback still seems to jitter a bit, but it appears to be in sync if the
MIDI synth has low enough latency.
Add support for Hugo's House of Horrors