add FemEnums.h
add ShapeMatrices
add NaturalCoordinatesMapping
include Eigen in Tests if OGS_USE_EIGEN
add TestShapeMatrices
add TestCoordinatesMapping
[NL] Move ShapeMatrixType into ShapeMatrices.h
[NL] Add missing iostream include.
[NL] Uncrustify.
[NL] Improve constness in NaturalCoordinatesMapping.
[TNL] ShapeMatrices: Use isZero/isOnes in tests.

Replace ASSERT with EXPECT.
add missing tests for ShapeMatrixType::DNDR and DNDR_J
improve readability of NumLibFemNaturalCoordinatesMappingQuad4Test
use isZero() and isOnes(), and divide CheckFieldSpecification to smaller pieces
Using constants known at compile time.
Switching loop sequence for optimization.
Merge pull request #225 from endJunction/add-natural-mapping

Add natural coordinates mapping.