Reduce duplication in src/categoryTools.js
Refactor plugin logic.

This relies more heavily on `async` and also makes the loading process more asynchronous. It does remove one warning in the case that a plugin is enabled but not installed.
Reduce DOM queries for Search elements
Refactor connection logic

Aiming to be flatter, with less deep nesting. Still more to go here.
Improve readability of a selector
Composer: Remove unused variables
Composer: Escape special characters in regex
Composer: Pass radix argument to parseInt
Add missing new lines at end of files.
Admin/Groups: Pass radix argument to parseInt