Add --as-needed flag to yade-lib.
Comment some lines, where defined unused variables.
CohesiveFrictionalContactLaw does not warn about incremental formulation of rolling/twisting moments when the moments are elastic
Minor fix in documentation of viscoelastic.
At every sync check,  whether ForceContainer is large enough.

In an very rare situation after boides were added conatiner can be
not resized even if _maxId was set.

Check on every sync() whether the container should be resied.
Disable parallel code in conditionalyEraseNonReal

This is done temporarly to fix/rewrite this part
of the code. Disabling at the moment because it
is critical. For details see bug-report:

https://bugs.launchpad.net/yade/+bug/1326288
fix bug in FlowEngine::updateBCs() (reported by Luc Scholtes, thanks)
Body::groupMask may be optionally boost::python::long_, subsequently modified code where necessary
fixed bug in yade.export.exportFacetsAsMesh (thanks Jan Havelka for reporting)
Merge github.com:yade/trunk into chaoUnsat