Opencl fixes

Closes lbmpy#9

See merge request !148

- corrected sorting 0.2.10 > 0.2.2

- tests are run in parallel to other jobs
  -> makes no sense to do performance testing there
  -> assertion randomly fails

Append assignments to KernelFunction (for later analysis etc.)

See merge request pycodegen/pystencils!140

cuda.TextureReference.set_array(tex_ref, cu_array) -> tex_ref.set_array(cu_array)

See merge request !134

Implement __hash__ for SympyAssignment

See merge request !142

Enable overriding of kwargs in SerialDataHandling.run_kernel

See merge request !143

Added guard around import to avoid failing when walberla is there but no python module is built

See merge request !147

FVM derivation: use a smaller stencil before trying brute-force to find the sparsest stencil

See merge request !146

Add remaining parameters from DataHandling.add_array to DataHandling.add_arrays

See merge request !138

Switch back to intersphinx sympy.org/latest ('coz it works)

See merge request pycodegen/pystencils!145

Fixed Volume of Fluid discretization and added Advection-Diffusion testcase

See merge request !141

Correctly print sp.Abs in generated code

See merge request !127

Use `rich` for syntax highlighting of `show_code` also in terminal

See merge request !139

Add assertion that headers follow the pattern /"..."/ or /<...>/

See merge request !137

CI: Replace minimal-ubuntu job with ubuntu

Closes #19

See merge request !135

Interpolation refactoring

See merge request pycodegen/pystencils!129