Add missing comma in envlist
Support models that use multi-table inheritance.

If a model implementing tree behaviour is subclassed, it is possible for the tree to contain a mixture of nodes which are instances of the subclass, and nodes that aren't. Consequently, when we call methods such as get_children, we need to ensure that the queries are performed on the base model rather than the node's own class.
Ensure that tree methods consistently return nodes of the same class as the original node, where proxy models are in use. (This was not the case for the AL backend's get_parent / get_ancestors / get_root methods)
Support models that use multi-table inheritance.
rename get_base_model_class to get_result_class and update comment to clarify behaviour re proxy models
Created new branch multi-table-inheritance

--HG--
branch : multi-table-inheritance
Merged in gasman/django-treebeard/multi-table-inheritance (pull request #12)

Support models that use multi-table inheritance
PEP8
Removed unused imports
Updating CHANGES