Merge pull request #407 from bvssvni/master

Optimize DataBuffer clear
Added get_components() method to the texture format. Fixed warnings.
Merge pull request #408 from kvark/tex

Added get_components() method to the texture format
static to const expr
Merge pull request #409 from MaikKlein/master

static to const expr
Update to rustc 0.13.0-dev 38517d0eb
Fix warnings 'static constant should be uppercase'
Merge pull request #411 from lucidd/latest-rust

Update to latest rustc and fix some warnings
Change fail! to panic!
Merge pull request #413 from lucidd/master

Change fail! to panic!
Fix missing_doc warning
Merge pull request #414 from darinmorrison/master

Fix missing_doc warning
-Fixed build break (&str -> str)
-Removed some warnings.
Merge pull request #415 from csherratt/master

Update to latest rustc
Implement buffer mapping

Does a big part of #236
gl-rs unsafety fallout

Closes #418
Implement cube mapping.

Closes #307
Implement compressed texture support

Actually compressing textures on-line will be deferred to a library such as
rust-image. Only supports the most important ETC2 formats, as these are widely
available (even on mobile), not patent-encumbered, in the core profile in
GL4.3+ and GLES 3.0, and have excellent quality.

Closes #332
Address reviews
Update glutin example.