Mac O'Brien

I license past and future contributions under the triple `MIT OR Apache-2.0 OR Zlib` license, allowing licensees to choose any one at their option.

[It looks like the upper limit on arrays of sampled textures is 128 for Metal](https://github.com/gfx-rs/gfx/blob/3fce1bd0550110f0565018fd2b4b74a4da151c62/src/backend/metal/src/lib.rs#L976). I was going to convert the UI shaders to use proper array textures later on,...

[Redox does return 0 for errno](https://github.com/rust-lang/rust/blob/master/src/libstd/sys/redox/os.rs#L37), and I think that makes the most sense here until we remove the function completely.