`fontconfig-rs` for locating fonts on Linux systems

[abonander]

I created a wrapper for freedesktop's fontconfig, which locates fonts on Linux systems based on configurable criteria. Hopefully it makes it easier to load fonts at runtime in programs using Conrod.

https://github.com/cybergeek94/fontconfig-rs/

I would have loved to make it cross-platform, but it currently only works on Linux systems, since fontconfig makes assumptions about the locations of essential configuration files.

Wikipedia says it's used on Windows in some programs, notably GIMP, so it should work cross-platfom with the correct configuration, but fontconfig-rs currently doesn't provide a way to initialize the underlying library with a custom config (that could be a TODO item if I had time to work on it).

[bvssvni]

@cybergeek94 You are awesome!