Disable key repeat if key catcher is 0

SDL1.2 branch disables key repeat when key catcher is 0.
Presumably to prevent binds from executing multiple times.

SDL2 replaced being able to disabled key repeat using SDL_EnableKeyRepeat
with a non-zero repeat value in the key event.
Merge branch 'master' (early part 1) into sdl2
Skip merging a SDL 1.2 commit into sdl2
Merge branch 'master' (early part 2) into sdl2
Skip merging a SDL 1.2 commit into sdl2
Merge branch 'master' into sdl2

Conflicts:
	.travis.yml
Merge branch 'sdl2' of https://github.com/ioquake/ioq3 into sdl2

Conflicts:
	.travis.yml