Unmaintained Reduce FontAwesome icon font file size

The instructions have been updated to suggest users create their own separate -reduced versions of the font awesome files, instead of replacing the original files on the server. Although this requires just a bit more work in editing templates, it has the advantage of forcing all users to download the new, smaller files, and will not trigger XenForo's file health warnings. Leaving the original files in place will also make it easier to undo your changes if you wish to start using the full font sets again.

Additionally, it is now recommended to edit the preload URLs in the font-awesome-setup template.

Added unlink, hdd, and fixed a typo affecting arrow-left. Python script's desiredGlyphNames array and core_fa.less updated.

Added align-justify, arrows-alt, arrows-left, and exchange. Thank you @OperaManiac for the tip.

Added align-center and align-right to the default icon list in the Python and CSS.

Added instructions to modify the setup_fa.less template file to force the new font files to be downloaded by visitor's browsers.