Added GH markdown for syntax highlighting in README

Looks a little better reading the small code snippets in the README with syntax highlighting.
Merge pull request #225 from ExPixel/patch-1

Added GH markdown for syntax highlighting in README
Merge pull request #226 from jameson-ernst/master

Add srgb framebuffer attr
Demos build again. Fixes #224
Expose the underlying SDL2 OpenGL profile enumeration values.
Merge pull request #228 from caryhaynie/add_gl_profile_enum

Expose the underlying SDL2 OpenGL profile enumeration values.
Use "let ref" with raw pointers and derive Copy when required

This is the minimal set of changes that is needed to compile this
project with the latest nightly. Many more structs will probably also
want Copy (as shown by the warnings), but I'll leave that for other
people to decide.
Merge pull request #229 from Gekkio/let-ref-and-copy

Use "let ref" with raw pointers and derive Copy when required
Bumped version number
Derive or ignore Copy for types that can implement it