Move Vf and Vmin from Body`s parameter to Body->state.

Only for compilation, where YADE_LIQMIGRATION is enabled.
Replace struct intReal by standard std::pair
Prevent returning of a real value from void-function.
Fix probably a wrong using of if-condition.
Minor fix of using of std::abs function.
Drop some if-conditions, which have always constant value.
Drop default inclusion of DFNFLOW.
Add some missing #ifdef YADE_CGAL.
Fix check-script for LIQMIGRATION.
Drop -frounding-math compiler flag from FindCGAL.
Many changes towards a more consistent sign convention throughout the code for stresses and strains. Should fix e.g. https://bugs.launchpad.net/yade/+bug/1381282. The goal is to know directly the meaning of a strain or stress value each time one is encountered. Relying on the classical Continuum Mechanics convention (editorial choice...). A global announcement is planned in a couple of days, in case some errors appear in the meantime.
Other changes regarding sign convention. Add of deprecation warnings (existing in the code and at execution) in the doc. Fix of script-session2.py previously broken
Drop embedded floating_point_utilities_v3.

All last boost-versions are having this headers already.
Now we are dropping Ubuntu 10.04 Lucid from now.
See https://bugs.launchpad.net/yade/+bug/1394942 answer # 3
Merge remote-tracking branch 'upstream/master'