Mesh refactoring

[tcreusc]

Phase 1: Mesh Status: @tcreusc to start working in it Tasks

• [x] Check if STL stuff still works #291
• [x] Move: Geometry directly to Mesh #308
• [x] Remove: createFromFile, setCoord, setConnec, coordElem #292 #293
• [x] Generalize: computeMinCellSize, computeMeanCellSize #294
• [x] Refactor: plot, LineMesh, SurfaceMesh, VolumeMesh #295

Notes

• kFace!! changes Geometry calculations
• Normals only when kFace = -1
• Can xFE become a P1Function instead of a P1Discontinuous?

Phase 2: SubMesh Status: @FerrerFerreAlex to further investigate on it Notes

• Create Submesh < Mesh, with
• P1Functions locally, LHS/RHS should be able to manage local to global. LHS should still be able to assemble locally.
• If test and trial belong to the same space, local. If test and trial do not, globally.
• innerMesh, innerCut, boundaryCut, ... are instances of Submesh
• P1Function can be created with a Submesh, when creating connec there could be two options (local/global)