c_schar is no longer in libc base export
Forgot one c_schar in sdl_image
Merge pull request #125 from mvdnes/schar_moved

c_schar is no longer in libc base export
~"foo" is removed
Merge pull request #127 from mvdnes/no_owned_str

~"foo" is removed
language changes: ~T -> Box<T>, ~expr -> box expr.

actually, this commit uses this breaking change as a chance to
modernize the API a bit: we no longer return redundant boxes
for most wrapped structs. this results in a slight API change,
thus the version has been bumped.