Genericons version 3.1

- Big migration release. Moves from using Glyphs Mini and manual labor to being generated by fontcustom (www.fontcustom.com)
- New directory structure that is cleaner, but also directed mainly by fontcustom output. Be mindful when you upgrade. This is a one-time change.
- genericons.css in the root folder is now deprecated, the file present just @imports the helper CSS from the new location, inside the font folder.
- README.txt converted to README.md for Github niceness.
- The 16px width/height is no longer baked into the helper CSS. It wasn't really necessary and caused headaches.
- Base64 encoding now included by default.
- Title attribute on example page.
- Unicode shown under icon on example page.
- New "website" icon.
- New "ellipsis" icon.
- New "foursquare" icon.
- Updated "show" and "hide" icons for clarity.