module for intersection + transport methods in moab

contains several utilities and "make check" tests
the core is the intersection class, Intx2Mesh, with 2 derived
classes, Intx2MeshInPlane and Intx2MeshOnSphere
it takes 2 mesh sets that overlap in plane or on a sphere, and 
creates an output set with convex polygons. Each convex polygon 
in the output set has 2 parents, each parent in one of the input sets
"convex" is understood either on a gnomonic plane of a 
sphere or in a plane

the input files can be visualized in visit or paraview, and for that we prefer 
conversion to vtk, if needed.
True writing/reading works in parallel only with hdf5 format

example for advection:
create_dp  ~/source/MOABsource/MeshFiles/unittest/mpas_p8.h5m HN16DP.h5m -t 0.1 -dt 0.05 

then 
intx_imesh 

mbconvert out.h5m out.vtk

compare the TracerAverage plot on HN16DP.h5m with the plot on out.vtk


