Fonts & Icons Inclusion

[rsh52]

This PR seeks to implement support for FontAwesome and Bootstrap icons. Free, open source licensed font files have been included under /inst and are installed and configured with the package.

List of changes:

• All related user-facing functions are under font.R
  • Associated tests under the test suite
• Developer scripts for creating/updating font files and their inclusion into the package are under data-raw/
  • Python's fontTools library incorporated to assist with unpacking TTF files
• Gallery and select pkgdown documents updated

Future considerations:

• A note occurs when running RCMD Check related to file size, due to the font files themselves. Since the intention is to have these available to users I'm unsure if this will be allowed or not.

Closes #60