Sprint todos

[ScSteffen]

Presprint TODO:

• validate PN in different cases against starmap

Sprint TODO

• Adding MPI
• Collided-Uncollided Split
• Running CT Scans with Triangular meshes (with Code of Chinmay)
• Validate & Check second order (if working, add to all methods / new branches)
• Prepare steps to 3D code (to fuse with Pias Matlab code) [IC, BC, Fluxes] (not high prio)
• Adding a beam test case
• Change Cell based flux to Face based Flux / Streamline mesh class for this case