Update to comply with refactoring of dune-python

Only merge once the upstream branch is merged.

See merge request !26

Feature/pandas integration

Add a script that allows to calculates performance regressions

See merge request !24

That allows us to load that file as a pandas frame.

Full test suite passes.

This fixes #29 

To achieve this goal, I did:
* switch to l2error comparison for all manufactured solution examples
* implement mixed expressions to allow that for systems
* fix `stokes_stress_symdiff`

The following issues remain, but the tests are deactivated until an upstream problem is fixed:
* `heatquation{_dg}_explicit` fails, new issue is #30.
* `poisson_dg_matrix_free` needs a suiting solver, depends on #31 kind of.

I also improved error handling: No more exceptions, instead non-zero error code. That way you get vtk output for failing tests (the previous behaviour was potentially harmful, as you could look at old solutions in debugging!!!).

See merge request !23

Instead return a bool that influences the return code

Switch all poisson examples to comparing l2 error



See merge request !22

Always enable timings



See merge request !21

Add time measure capabilities

Fixes Issue #23.

See merge request !19

Feature/ini options

* Read formcompiler options from ini files
* Have a systemtest macros allowing variation in formcompiler arguments
* Rewrite the test suite using it

Exhibits some more problems in our test suite.

This fixes #1.

See merge request !20

[cleanup] Make function names more consistent

Small name changes. I succesfully ran all tests.

See merge request !18

Add heat equation DG tests

The dirichlet_boundary Expression in the UFL file will be used as initial condition. PDELab figures out that it dosn't need any constraints.

See merge request !17

Use the caching infrastructure for registering function manglers

This fixes #14 

See merge request !16

Feature/cellwise constant

Make it possible to mark Expressions as cellwise const and put evaluation in pdelab outside the quadrature loop. Closes issue #27.

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.

See merge request !14

Feature/modernize cache infrastructure

* use local storage instead of global one
* Remove cache context
* Remove cache item types
* Introduce cache inspection method

See merge request !15

They are concepts that are not really necessary with local
storage, that I do not really want to explain to other people.

Only register generators globally. This makes inspection of cache
items much easier.

Feature/evaluate basis gradient with loopy 2

Second try to implement issue #22. We avoid problems with diagonal matrices in the following way:

1. The user can give the option 'diagonal-transformation-matrix' to the form compiler if he wants to reduce the loop.

2. It is now possible to set options during the form compilation. When a YaspGrid is created we automatically set the option 'diagonal-transformation-matrix'.

Usually it makes little sense to provide the information yourself. I just wanted to add the possiblility if someone has a axiparallel grid that cannot be a Yasp Grid (eg. due to non rectangular domain).

Closes issue #22.

See merge request !13