Rename ._uflclass -> ._ufl_class_ for consistency with new type traits.
Use expr._ufl_is_terminal_ instead of isinstance(expr, Terminal), slightly faster operation for proof of concept.
Comment about index sorting confusion.
Replace .operands() -> .ufl_operands everywhere.
Use new UFL indexing model.
Some optimizations.
Removed UtilityType from ufl.
Change 0-0.0. Some comments. Sketch a new partition generation variation.
Add gtest-1.7.0 to the source tree.
Make some of the failing unit tests pass.
Make some of the crosslanguage tests pass again as well.

Assuming gtest built locally.
Allow manually set GTEST_DIR, or set to local copy of gtest. In the
latter case gtest must be built in the local dir as described in README.