Fenics-ufl

- Fix bug in propagate_restriction

- Several interface changes in FormData class
- Introduce call preprocess(form) to be called at beginning of compilation
- Rename BasisFunction --> Argument
- Rename Function --> Coefficient

- Redefine grad().T --> grad()
- New meaning of estimate_max_polynomial_degree
- New function estimate_total_polynomial_degree
- Allow degree = None and cell = None for elements

- Extensions for ElementRestriction (restrict FiniteElement to Cell)
- Bug fix for lhs/rhs with list tensor types
- Add new log function set_prefix
- Add new log function log(level, message)
- Added macro cell integral `*dE`
- Added mechanism to add additional integral types
- Added LiftingOperator and LiftingFunction
- Added ElementRestriction

- Some critical bugfixes, in particular in differentiation.
- Added form operators "system" and "sensitivity_rhs".
- diff can take form as argument, applies to all integrands.
- Rudimentary precedence handling for better
use of parentheses in str(expression).
- Added script ufl2py, mainly for debugging purposes.
- Crude implementation of estimate_max_polynomial_degree
for quadrature degree estimation.
- Improved manual.

- Initial release of UFL.