Add Gridview, clean UI, QoL changes.

+ Added a grid view to the main UI that will show all the various
animations the user can choose from.
+ Changed main theme from light to dark.
+ Cleaned UI, made it prettier. Still needs work.
+ Made quality of life changes on the code to make it cleaner and more
readable.
- A lot of work still needed.
- The first time ever the app is created, it is placing the animation in
the top left corner. Needs to be fixed (I've done this before, so its a
regression).