added debug logs for topology creation, fixed monoprocess field requirements for domain splitting, added discretization to logs

fixed 2d multiscale opencl advection, implemented spectral multiscale lowpass filtering in python and opencl

Resolve "Nested Problems"

Closes #32

See merge request !18

Merge branch '11-sine-and-cosine-transforms-to-solve-homogeneous-neumann-and-dirichlet-problems' into 'master'

Resolve "Sine and cosine transforms to solve homogeneous Neumann and Dirichlet problems"

Closes #11

See merge request !3

Merge branch '11-sine-and-cosine-transforms-to-solve-homogeneous-neumann-and-dirichlet-problems' of gricad-gitlab.univ-grenoble-alpes.fr:particle_methods/hysop into 11-sine-and-cosine-transforms-to-solve-homogeneous-neumann-and-dirichlet-problems