Initial bounds support
bounds: load world coordinates
Add missing volume_info.go

Also fix an error with the scaling factor
Collections interface extended/cleaned up
Collections interface extended/cleaned up

Conflicts:
	main.go
	resource/drawable/shader/group.go
bounds: A bunch of fixes

Also begin writing the new export interface
Fix bounding cube generation
Merge branch 'master' into bounds

Conflicts:
	main.go
	resource/drawable/shader/group.go
Migrate drawable export to the new api
Add user configurable Y/Z flip