Feature/cellwise constant
Make it possible to mark Expressions as cellwise const and put evaluation in pdelab outside the quadrature loop. Closes issue #27 (closed).
The implementation is kind of sketchy but I wanted to go to weekend. Some notes/TODO:
- I had to add a statement to the ufl file. For cellwise const expressions a dg0 dummy space is used (-> cell wise const), else we use a dg1 space (in execution.py).
- I now use 'default_declaration' from loopy.py for defining parameter objects.