This fix also includes:

• Add alias in fontawesome mapping file, which means outdated font names (alias) will be usable in PyWaffle.
• Move font-related text handler out of waffle.py, and it will only be imported when Font Awesome is used. It will help boosting the loading speed as Font Awesome should be a relatively less common use case.
• It is (slightly) easier to upgrade Font Awesome package separately now, as users only need to pip update fontawesomefree, while they still need to execute fontawesome_mapping_generator.py under the package folder to refresh mapping file.

This change will also erase the need of upgrading Font Awesome like in #27 and #10, as there's no more embedded fonts.