Added method to check if key is currently down

Signed-off-by: Martin Grönlund <martingronlund@live.se>
Merge remote-tracking branch 'remotes/origin/Input'

Conflicts:
	MartinPeterSDL.suo
	MartinPeterSDL/MartinPeterSDL.vcxproj
Solved conflicts

Signed-off-by: Peter Mårtensson <veritas.is.me@gmail.com>