Determine version of Metis library. Apparently, at least version 5.x is needed for Eigen/MetisSupport.
Marked some internal variables as advanced

Adding missing OPENGL_LIBRARIES for openglsupport test. Also adding OpenGL include directories as a better pratice even though these are system include directories in most systems.
(grafted from 1a0b070721bc403eefb6a1cc28c78169e8518715)

(grafted from 501e6f168055a3d7782730c1ade00b8f853a1a0d)

UmfPack support: fix redundant evaluation/copies when calling compute() and support generic expressions as input

(grafted from 9d33229cfb960f4272de8dad046f75873723751e)

(grafted from 8ba3b2cf2df84e9e69bc0b7ee3172ed4833cdb47)

(grafted from c303363d178956db60ea7a21c88b36b20f5d6560)

Fix Hyperplane::Through(a,b,c) when points are aligned or identical. We use the stratgey as in Quaternion::setFromTwoVectors.
(grafted from d9af749994e161380b1bc281dccc0be93fe3f082)

(grafted from 1d72cb9b08c13d0c344fdad2a43a91aaf89fa7c5)

re-enable usage of ProductBase::m_result and workaround a compilation failure when m_result is too large but unused