inlined free functions
added cmake options to specifically build mesher kernel libraries

zb: -DBUILD_EXTERNAL_LIB_TRIANGLE=ON -DBUILD_EXTERNAL_LIB_TETGEN=OFF -DBUILD_EXTERNAL_LIB_NETGEN=OFF -DBUILD_EXTERNAL_LIB_VGMODELER=OFF
Merge branch 'devel'

Conflicts:
	viennamesh/core/parameter.hpp