* New version of Trevor Strickler's QuadTri patch (+ examples in benchmarks/extrude_quadtri)

* First pass at SU2 mesh export

HexReferenceSpace seems to Work: other test passed -- ReferenceSpace and PermutationTree: need to compress tag if they do not form a continous sequence -- HexNodeBasis: reworking with new framework -- PermutationTree: start serialization

ReferenceSpace for Hex: Seems OK \o/ -- ReferenceSpace uses now connectivity check instead of parallel face -- Need check with HexBasis

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