Changeset [634a004497c915f5f5b7a3f76e198d68dbd9dc83] by Jed Brown

Add ValueCache to handle copy and no-copy mapping between orderings.

If a single-patch quadrature is not used, the values should be mapped
from quadrature points in element-natural ordering to quadrature points
in patch-natural ordering.

ProjResidual2 uses a funny interface that forces many details on the
user, I have deactivated it in this commit, it may be removed later.
https://github.com/jedbrown/dohp/commit/634a004497c915f5f5b7a3f76e1...