edge type for distance queue creation

[cwsmith]

The distance queue appears to be created over the 'primary' edge type:

EnGPar/partition/Diffusive/src/engpar_queue.cpp

Line 254 in f96ddea

agi::etype t = 0;

For a mesh the different edge types should produce very similar distances. For non-mesh inputs having a parameter for the edge type could improve the results.