Glyph lifetimes for Font::glyphs_for & Font::layout

See merge request !158

Improve Font::layout lifetime bounds

Closes #151

See merge request redox-os/rusttype!156

Update ttf-parser to 0.6

Closes #149

See merge request !155

Update kerning logic

* Add single_ttf, single_otf benches.
* Adjust thrashing size to new fonts.

This show the poorer performance of rusttype's handling of otfs 
currently compared to ttfs.

Use owned_ttf_parser crate

See merge request redox-os/rusttype!154

Push unsafety out of rusttype to the very specific usage in the
dependency.

Implement Support for building outlines

See merge request redox-os/rusttype!153

This brings back support for building outlines, which disappeared in
rusttype 0.9.

Exo2 ttf vs otf

See merge request !152

Support .otf fonts by switching to ttf-parser & ab_glyph_rasterizer

Closes #137

See merge request !151

* Rename "rusttype-dev" private crate "dev"

Update changelog

* Add Exo2-Light.oft refrence tests & benchmark.
* Update readme.
* Remove crate rasterization logic.
* Update render references (byte differences, visually the same).

Implement Default for the geometry structs

See merge request !150

Remove arrayvec dependency

Closes #146

See merge request !149