#169 Measures the shortest distance between two entity selections in HyperMesh tcl

To get the shortest distance between nodes 100-200 and nodes 300-400:

*createmark nodes 1 100-200
*createmark nodes 2 300-400
hm_measureshortestdistance nodes 1 0 nodes 2 0 0

To get the shortest distance between surface 100 and lines 1-10, with the distance output relative to system ID 5:

*createmark surfs 1 100
*createmark lines 1 1-10
hm_measureshortestdistance surfs 1 0 lines 1 0 5