Add several functions to interact with animations using strings

[DaQueenJodi]

I noticed there was a name field on the Animation struct, so I figured it would be useful to use it to set the current animation, get the name of the current animation, and be able to get the index from the name i wasn't sure what to call the functions, but hopefully these are fine.

[DaQueenJodi]

it may be better to take a &str for each function, which should be pretty easy to change I decided to use a String for all of them since get_current_str() would need to return a String and not a &str, but that may not be that important

[DaQueenJodi]

alright, just changed those 2 to take a &str

[DaQueenJodi]

I also just added a way to get the number of frames in the current animation, which could be useful, would you want me to commit that to the PR as well?