add a shape function class for quad4
add Tests/NumLib in CMake
add a test for ShapeQuad4
add FemEnums.h having ShapeFieldType
add a struct storing shape function matrices
add a class responsible for mapping between physical and natural coordinates
add FindEigen.cmake
add CMake options OGS_USE_EIGEN
cofigure Eigen in travis
add write() to Shapedata
log output only in debug mode
add macro OGS_USE_EIGEN
include Eigen in Tests
add a test for ShapeData
add a test for coordinates mapping
add FindEigen3.cmake
use FindEigen3
fix eigen3 include dir
use ASSERT_ARRAY_NEAR