Change variable names in Eigen3Config.cmake to EIGEN3_*

--HG--
branch : vladimir_ch/bug-796-fix-eigen3config.cmake
Merged in vladimir_ch/eigen/vladimir_ch/bug-796-fix-eigen3config.cmake (pull request #67)

Change variable names in Eigen3Config.cmake to EIGEN3_*
Update decompositions tables
Fix Jacobi preconditioner with zero diagonal entries
fixed warning: -Wunused-local-typedefs