Add support for adding/removing animations

[MishaProductions]

[nptr]

I've only given it a short look. The UI / usability is a bit awkward in my opinion. For example:

1. Figuring out how to add & remove an animation took me quite some time. I expected a menu in the class view rather than the property view.
2. I am unsure if its a good idea to specify both part id and state id in one dialog rather than a separate state menu/dialog.
3. Removal of an animation didn't work well for me. Some animation were deleted, others not.

Those things are more a structural problems in my opinion, because msstyleEditor doesn't provide the menu's and facilities that i think would fit better. I'll revisit this PR some time later and possibly more clearly elaborate on my findings.