Wider Professions - Better Window and Filters

Added support for hunters!! You can now train yours pets again and enjoy all the features that were introduced for professions.

For example: search bar for abilities, cleaner interface, filters, new cateogories to remove clutter, slightly-extended vanilla-like color-coding to identify find skills that can be trained, but the requirements are not met yet, easily see how many training points are available, and customization of the window to your lovely pet :)

Also, improved vanilla-feeling by:

Adding some sound effects for when interacting with buttons/checkboxes etc.
Adding vanilla text (hidden in the skills menu) that appears when you hover the progress bar.
Improved interplay with other frames, notably being pushed around by loot windows, now they are pushed instead.