Two major changes in this version. First stroid now embeds a vacuum coordinate as part of its StroidMesh file (this is a packed set of mfem meshes and GridFunction). This is a logical coordinate from 0 at the stellar surface to 1 at the mesh surface / compactified infinity which can be used by consumers to much more stablly infer position in the vacuum region. Second, there is a new topology backend, multi_block, which has been made the default. See the readme for more information but the basic jist is that multi_block addes 6 transition blocks onto the edge of the core domain. This allows for a much more well conditioned transition from the internal cartesien region to the external spherical region. The mesh conditioning improves by roughly a factor of 1000 for the same refinement level when compared to the legacy topology. The legacy topology is maintained as a option if core_mapping is set to spherified in the config.
Test suite has been updated to include a much more robust suite of tools for validating mesh quality and mesh usability (including but not limited to things such as validating that integrating over a sphere provides the correct volume, that the mesh is confirming, and that no elements are inverted)
Stroid can now generate vacuume regions. These are confirming spheres marked with a seperate attribute that solver may then apply arbitrary mappings to. Further, the boundary of this region is also marked with a seperate boundary attrite allowing seperate boundary conditions to easily be applied.
stroid generates o-grid topologies with proper boundary conditions applied. Currently the external domain does not work, this will be addressed in the next commit.
