gfx: Refactor the Mac platform goop into platform/
Refactor the Linux font stuff
Remove native.rs. It's no longer needed; just use platform::* directly.
Remove some module aliases.

These aliases were there for old versions of resolve, and are no longer needed.
Refactor glyph.rs to modern Rust coding style
Refactor the HarfBuzz shaper to be in line with modern Rust style
Rename one of the two modules called "shaper"
Hoist all `extern mod` directives to the top level

This improves compile time and makes `use` directives look cleaner.
Nuke the TGA encoder
Add missing platform/mod.rs
Merge pull request #365 from brson/master

Update submodules
submoudle: update latest rust-azure, skia
Merge pull request #367 from yichoi/pull-0416

submoudle: update latest rust-azure, skia
added --enable-debug flag to mozjs
Update rust-azure
Merge pull request #368 from aydinkim/352

added --enable-debug flag to mozjs
fix image element to work
Merge pull request #369 from aydinkim/301

fix image element to work
Merge pull request #370 from brson/incoming

Update rust-azure
Move generic util code from servo-gfx to top-level servo-util.