Initial implementation of an addons manager

When loaded, will load all auto-load marked UIs.  Shows current UIs and
allows custom UIs to be loaded.
Auto-load Addons

The addons mod is now auto-loaded (by character.ts) and will auto-load
any mods listed in modules-list.js as autoload.
Sexy Scroll Bars

Just add class="sexyscroll" to your scrolling elements to get a cleaner
looking scroll bar.
Merge branch 'feature-sexyscroll' into test-mods