Fix bug where cursor could be freed more than once
Move sprite_t to dos_sprite_t
Add Travis CI configuration file
README: Add build status from Travis CI
Merge branch 'travis-ci'
sdl-video: Move sprite_t conversion to gfx.c

Sprite caching is moved to gfx.c as well.
sdl-video: Move all palette use to gfx.c
sdl-video: Move sprite masking to gfx.c
gfx: Merge sprite caches into single hash table
sdl-video: Merge all sprite drawing functions into one
Fix: include misc.h in gfx.h for uint definition
Merge branch 'gfx-sprite-move'