Todo list: Half-baked bits

[Fuzzyzilla]

There's a couple of things that are 50-90% implemented that i stopped and merged because i got worn out/burnt out that I really must revisit and spring-clean. Todo list :3

• Partial state clones - left as a todo!() but never used. Could present a substantial performance boost on large documents (which given the state of things is not likely to be a problem in the app's current form :P)
• File IO - left as a skeleton that saves and loads the bare minimum to prove to myself that it was "working"
• Object pickers - got real bogged down in API design and after completely stagnating I merged it to avoid divergent histories. Never called into.
• Text rendering - similar story as above. Also some ecosystem problems, trying to find a font database, and recently learned that rustybuzz is deprecated D: