A bit changed material description in task file
Introducing mutable and immutable rheology matrices. Implemented
isotropic and anisotropic matrices using immutable rheology matrix.
Merge remote-tracking branch 'origin/master'

Conflicts:
	src/libgcm/util/AnisotropicMatrix3D.h
Add .refresh() call, fix unit tests for anisotropic matrixes
Fix memmory leak in AnisotropicMatrix3D
Naive tests for analytical vs numerical matrixes for anisotropic materials
Update AnisotropicMatrix3DAnalytical implementation
Merge remote-tracking branch 'akazakov/master'
Merge remote-tracking branch 'upstream/master'

Conflicts:
	src/tests/unit/anisotropic_matrixes.cpp
New test AnalyticalVSNumerical.