* Inital proof of concept on the item group api
* Some changes
* Show hotbar tab + fix bug with inv slots not clearing out
* Better button textures + docs + tweaks/auto format
* Add an api to provide the stack to display and expand the example mod
* Use COMMON_GROUPS in all places
* Add a tooltip showing the page numbers
* An initial implementation for colour mapper registries
There's elements I'm still not entirely happy here, but it appears to
work as expected.
* Add a test mod for colour mappers
* Fix license violations
* Rename everything to correspond with future names
* Woops