New and shiny update and export logic

[dan283]

• [x] New combined update
• [x] New inbetween update
• [x] Negative shape support
• [x] Inbetween combo support
• [x] New export logic

[dan283]

Needs cleanup but working. I'll leave that to another task as we're still in alpha here and I don't want to delete stuff without proper testing.