Merge pull request #90 from bvssvni/master

Upgraded to latest Rust
Merge pull request #91 from bvssvni/master

Added `top` and `left` methods on `Character`
Merge pull request #92 from bvssvni/master

Added `advance` method to `Character`
Merge pull request #93 from bvssvni/master

Replaced `glyph` and `bitmap_glyph` with `size` and `offset`
Merge pull request #94 from bvssvni/master

Use type alias to `Character` in graphics
Merge pull request #95 from bvssvni/master

Implemented `CharacterCache` for `GlyphCache`
Fixed compilation error: added documentation to type aliases.
Merge pull request #96 from thebreadcat/master

Fixed compilation error: added documentation to type aliases.
Add preload_chars and preload_printable_ascii, closes #100
Quick fixes
Reexported `OpenGL` from shader_version

Closes https://github.com/PistonDevelopers/opengl_graphics/issues/99