Rework accumulation splitting

See merge request !119

[bugfix] Fix non-editable installations

Closes #72

See merge request !118

In the end I had to combine the last two versions. For jacobians:
- We want to split according to the FunctionView (e.g. Stokes).
- We don't want to split according to gradients (e.g. sumfactorization).

Implement register transpose of 4 AVX512 register

See merge request !120

Example: Before this commit the expression

\sum_i a_i (\nabla v)_i + \sum_j b_j (\nabla v)_j

was split into two accumulation terms:

1) a_k with corresponding test function (\nabla v)_k
2) b_l with corresponding test function (\nabla v)_l

Now we split into:

a_k + b_k with corresponding test function (\nabla v)_k

This is possible since we have linearity in the test function.

TODO: Jacobians are not yet working

... by listing all packages manually in setup.py

Feature/restructure applications

See merge request !115

Its not worth the hassle rihgt now.

Feature/refactor manual cse

See merge request !114

But only when they are actually used!

Feature/volumes as constants

See merge request !113

Fix ADL problems

See merge request !112

Feature/diameter handler

Closes #66

See merge request !111