Implement Renderer::read_pixels, Texture::lock, Texture::unlock.

[andelf]

This fixes #10 .

• also add SDL_version support

[andelf]

partially fixes #64

[andelf]

I use CVec<u8> as the underlying pixels format. A better implementation might use type parameters. like:

pub trait Pixel {... } // stands for a single pixel
pub struct PixelRGBA8888 { r: u8, g: u8, b: u8, a: u8 }; // same size as underlying bytes
impl Pixel for PixelRGBA8888 {... }

let tex = renderer.create_texture::<PixelRGBA8888>(...) // got Texture<PixelRGBA8888>
tex.lock(None) // got CVec<PixelRGBA8888>

[AngryLawyer]

Excellent! Thanks :)