start implementing mesh and fem
now it loads mesh data from a OGS mesh file.
FEM test codes for steady state diffusion equations only for triangle elements. It works.
fix compilation error in MSVC2005
use SOURCE_GROUP in CMake to usethe Filter function in MSVC
save
fix compilation error on linux. actvate omp
revert changes in sparse matrix classes
save
parallel for
forgot to stop timer
use Eigen::MappedSparseMatrix
Merge remote-tracking branch 'ogs6-master/master' into temp1
on the way to use CRSMatrix instead of Eigen
Merge remote-tracking branch 'ogs6-master/master' into temp1
fixed a MSVC error
Merge remote-tracking branch 'ogs6-master/master' into temp1

Conflicts:
	CMakeLists.txt
integrated CRSMatrix
fixed
Memory of matrix will be deleted later