Added a from_read() method to RWops
Added a from_read() method to RWops

The ownership is a little squirrelly but this seems the best way.

Cobrand/rust-sdl2,AngryLawyer/rust-sdl2,Rust-SDL2/rust-sdl2,Rust-SDL2/rust-sdl2,Rust-SDL2/rust-sdl2,oldmanmike/rust-sdl2,Cobrand/rust-sdl2,Cobrand/rust-sdl2,vadixidav/rust-sdl2