added ymport.iges function for reading facets from .igs files
updated timing documentation
updated documentation (due to recent changes in Cpm), corrected Cpm related examples
correcting compilation errors from previous commit
Handle the cohesive contact between a sphere and a facet.
Created Ig2_Facet_Sphere_ScGeom6D inheriting from Ig2_Facet_Sphere_ScGeom. It precomputes the 3 rotations DOFs and creates a ScGeom6D contact geometry.
All modifications made into /pkg/dem/Ig2_Facet_Sphere_ScGeom.cpp and hpp.
Update link for tarballs-download.
Changes in Grid.ccp/hpp.
- Improve documentation for Ig2_Sphere_GridConnection_ScGridCoGeom::go()
- Add a new law (Law2_ScGridCoGeom_CohFrictPhys_CundallStrack) that allows a cohesive contact (without rotational moments) between a Sphere and a GridConnection.
fixed bug in Cpm for Sphere-Facet interactions
fixed bug in Cpm, now for Sphere-Wall interaction
Merge remote-tracking branch 'upstream/master'

Conflicts:
	pkg/dem/ConcretePM.cpp
	py/timing.py