Cython Rewrite

This release removes the python version of the NBT library and massively rewrites the cython library.

This should be backwards compatible with the old version but some features are depreciated and renamed.
NBTFile has been depreciated and replaced with named versions of the tags. NamedCompound for example.
These behave like the old NBTFile but the value can only have one type. This was done because the type in the NBTFile was ambiguous.
The NBTFile used to have a value attribute. This has been renamed to tag in the named variants. value still exists but is depreciated.
The tags used to also have a value attribute. This has been renamed to py_data to be more clear. value still exists but is depreciated.

The new version should behave more like the python types. Some of the behaviour was missing in the old version.