[WIP] Implement a finite element space–agnostic semi-Lagrangian variational advection step for scalar fields, working on both volume meshes and surface meshes. Method outline: Inputs: - Mesh with element maps F_K: reference element -> physical element. -...

[WIP] Implement a finite element space–agnostic semi-Lagrangian variational advection step for scalar fields, working on both volume meshes and surface meshes. Method outline: Inputs: - Mesh with element maps F_K: reference element -> physical element. -... #726