Another instance where SDLK_XX needs to be converted to the SDL_SCANCODE_XX.
Convert icon from the indexed color representation into 32-bit
RGBA array. This simplifies initialization.
It's unclear why did I put "doscreenupdate()" into the kbhit routine,
it certainly does not belong there.
o Get rid of unused rootpal;

o implement fullscreen mode;

o implement window icon.

This makes SDL 2.0 pretty much on par with SDL 1.2 version, if
not better.