Make UIDMeta require a UID and type to instantiate
Use a callback chain to sync tag UIDMeta objects instead of manually keeping indices
Update comments in TSMeta.LoadUIDs
Replace the databinding deserialization of UIDMeta objects with a manual tree deserialization
Restore single class imports
Merge pull request #62 from hi3g/valid_uidmeta

Force valid uid and type of UIDMeta object on instantiation