- Changed Surface#get_colorkey to Surface#colorkey to be consistent with   Surface#alpha and Surface#set_alpha. - First attempt at documentation comments in RDoc format.
- Changed Surface#get_colorkey to Surface#colorkey to be consistent with
  Surface#alpha and Surface#set_alpha.
- First attempt at documentation comments in RDoc format.


singpolyma/rubygame,firstval/rubygame,singpolyma/rubygame,Dami-coding/rubygame,rubygame/rubygame