make sure vertices aren't mistreated in split_nonmanifold
smoothing
tiny tweaks for smoothing
stuff
cleaned smoothing
make cotangent weights work; pre-commit for overhaul
clean and update smoothing code to something that semi-resembles a reasonable solution. either weightings or numerics/solver are still not right.
comment out unused helper functions
RawArray: Add a missing RawArray<T,3> constructor

Also add a few missing asserts.