Adds minimal support for SDL's RWops. At the moment, only 2 functions are implemented:

1) RWFromMem(but []byte)
   Creates a RWops from memory

2) IMG_Load_RW(rwOps *RWops)
   Loads an image from an RWops
Adds minimal support for SDL's RWops. At the moment, only 2 functions are implemented:

1) RWFromMem(but []byte)
   Creates a RWops from memory

2) IMG_Load_RW(rwOps *RWops)
   Loads an image from an RWops
fixed comment
removed unused imports
Merge pull request #2 from asig/master

Add support for RWops