Beta 3 stable

This adds nothing but some typos I forgot to check for in the previous release, which does not get a number update given the edits aren't relevant.

ThunderBoard beta 3

• Removed the bug report manager, which was faulty;
• Edited the automatic variable recognition algorithm with a more precise one which should not strip valid JS code anymore;
• Edited the loading indicator, dropping NProgress in favor of Spin.js. In the future, spinners might be customizable by the final user;
• Added support for page-specific stylesheets;
• Minor bug fixes.