Move mesh fetch out of loops.
Add new Mesh method boundary_fes_by_oshape_side.
Changed f64::NaN to NAN to follow Rust's rename.
Add IterByes auto-derive for FENum, NBSideNum, SideFace.
Move inner products needed by the projector into the basis, so projectors will be inexpensive to construct.
In LaplaceVBF, replace projector constructor param with wg basis.
Remove unused variable.
Add fold variant with enumerated terms.
Rename LaplaceVBF -> VBFLaplace.
Solver mostly done.