UI Features for v0.2.0

[njbrown]

This pr contains all of the ux features outlined on itch.io

Graph:

• [x] Multi-Selection
• [x] Copy/Cut/Paste
• [x] Undo/Redo
• [x] Comments
• [x] Frames (Few missing features)
• [x] Spacebar Node Menu (almost done, needs styling)

UI:

• [x] Navigation bar with undo/redo and export buttons

note: Some features were excluded for the sake of time and will be added in an upcoming minor version.

[iKlsR]

Clean to di bone skeleton bone. 🦴