Rename add_record to new_record
Add extra_attributes helper
New add_record method
Implement custom hash function on ProvRecord
Fix flattening
Update history
Extracting the attribute order from the class definitions.
Compat for Python 2.6.

No dictionary comprehension in Python 2.6.
Nicer node labels during plotting
Added test for the prov:other element.

And removed the corresponding example from the examples folder.
<prov:other> tags will now be ignored.

A warning is raised to inform the user, but otherwise this is desired
behaviour.
Merge branch 'master' into prov-xml

Conflicts:
	prov/model.py
Adapting to changes in master