Added code that disables C128 BASIC's sprite-motion interrupt-handler.

That lets the mouse drivers control a sprite directly through the VIC's registers.
Merge pull request #90 from greg-king5/c128-sprite

Added code that disables C128 BASIC's sprite-motion interrupt-handler.
Removed references to $TRAVIS from Makefiles.

After all it seems much cleaner to explicitly control the behaviour from the .travis.yml file than to behave differently "under the hood" when detecting a Travis CI build.