#265 *markintersection in HyperMesh tcl

*markintersection determines the intersection between two marks and stores the results in the first mark in HyperMesh tcl.

To delete the intersection between the elements on marks 1 and 2:

*createmark elems 1 1 2 3 4
*createmark elems 2 4 5 6 7
*markintersection elems 1 elems 2
*deletemark elems 1

This will delete element 4.