Mesh splitting and selection

[PProfizi]

Introduces Meshes, a container for multiple Mesh instances (wraps a MeshesContainer).

The goal is to allow for lazy Mesh queries, where a first splitting step is used with a further selection to work only on the MeshedRegion of interest.

Adds Mesh.split_by_properties(), Mesh.select(), Mesh.plot() Adds Meshes, Meshes[{"mat": 1, "elshape":1}] or Meshes[0], Meshes.plot()

To do:

• [x] Treat split by with specific property values
• [x] Improve coverage
• [x] Improve documentation
• [x] Add example

[codecov[bot]]

Codecov Report

Merging #346 (3e271a4) into master (7917821) will increase coverage by 1.84%. The diff coverage is 97.92%.

@@            Coverage Diff             @@
##           master     #346      +/-   ##
==========================================
+ Coverage   81.64%   83.49%   +1.84%     
==========================================
  Files          39       44       +5     
  Lines        4124     4640     +516     
==========================================
+ Hits         3367     3874     +507     
- Misses        757      766       +9