Initial implementation of VertexFormat trait and the deriving attribute
Mesh macro - Partially implemented type decoding, improved general structure.
Mesh macro - offset computation, type parsing with attributes
Mesh macro - cleaned up the old mesh Builder, imported stuff from mesh namespace directly, fixed the example.
Mesh macro - refactored field modifiers with syntax::mark_used, pre-allocated the result vector
Rename iter_errors to errors

According to the guidelines, methods returning an iterator should
not have extra prefixes, just a plural noun.
Merge pull request #123 from cmr/master

Rename iter_errors to errors
Added macro test module
Added create_mesh() convenient method, used in the triangle example
Merge pull request #122 from kvark/vertex

Vertex format generator macro
Clean up code in gfx_macro::mesh and make gfx_macro::mesh::decode_type more robust.
Improve documentation
Clean up formatting
Use quote macros to make #[vertex_format] implementation clearer
Improve project structure

`gfx_macros` is more consistent with the standard library's `regex_macros` crate.

The submodules in `gfx_macros` are now named after the attributes that they implement.
Use quote_expr! more extensively
Do not allow uint and int component types
Fix comment
Merge pull request #124 from bjz/macros

Assorted cleanups to macro implementations and project structure
Add lots of docs