[FO4] Improved Vertex Format support

Supports several edge cases at the cost of being more complicated since
the XML is not set up to allow testing of multiple flags in compounds.

Now loads SCOL with crashing NifSkope and without any errors.  The
PreCombined folder now at least opens but with errors as
BSPackedCombinedSharedGeomDataExtra is not decoded.

Much wider support of meshes overall, without any NaN issues stemming
from misassignment of half float types.