FontAwesome RemarkupBar

Summary:
Replaces the icons with fonts from FontAwesome. Up in the air about the meme icon. Thoughts?

Also removed the second fullscreen/normal state. Seems obvious what it does, but assume someone complained previously?

Test Plan:
Tested all the icon states and made sure they still worked. Test fullscreen and help.

{F163485}

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9385

scripts/celerity/generate_sprites.php

@@ -27,7 +27,6 @@ $webroot = Filesystem::readablePath($webroot);
 $generator = new CeleritySpriteGenerator();
 
 $sheets = array(
-  'remarkup' => $generator->buildRemarkupSheet(),
   'menu' => $generator->buildMenuSheet(),
   'apps' => $generator->buildAppsSheet(),
   'minicons' => $generator->buildMiniconsSheet(),