Volume-Edge Ratio Quality Measures

[sjkelly]

See: https://people.eecs.berkeley.edu/~jrs/stellar/KlingnerPhD.pdf

The current quality implementation relies on tetrahedra -> triangle decomposition. In the 2D case this is fine, but in the 3D case we need to create a unique set of primitives just for this quality measure. Volume-Edge ratio might be simpler. There might also be a way to use the preexisting edge length calculations.

[sjkelly]

Prospectively, with this measure not only out-of-boundary tets can be filtered, but also low quality ones as well