GEN3D: extrude 9-node quad mesh to 27-node hexes

[gsjaardema]

Greg,

Okay, good to know.. I would need this capability at the start of Q3 (this
year) in support of my VVUQ project. I may have alternative paths in
Percept, however, let me check on that... I think that Percept might promote
a mesh from P1 to P2. We certainly support arbitrary promotion in Nalu now
(P1->P12-ish) however, that is internal to the code and for my VV study I
want a pure quadratic hex mesh.

Best,

Stefan

[gsjaardema]

Not a priority at this time.