[FL] Removed mutable type specifier

[FL] Simplified some calculations and changed the documentation

according to Dima's comments.

[FL] Corrected a documentation for an argument of the member of getdValue

add the unconfined compression test compared with analytical solution

The local NewtonRaphson is moved from MaterialLib/SolidModels to NumLib in order for further reusing.
This class provides a basic NewtonRaphson routine to handle the nonlinear constitutive relationships existing in the local problem. After being moved to NumLib , it can be reused by other processes, e.g the two-phase multicomponent process which I am working on now.
(p.s. Some of the changes are caused by running clang-format)

Otherwise std::unique_ptr was not found on gcc 4.8.1

Conflicts:

	Tests/Data

The solution is rather slow, but working. The latter is important for
the large tests CI.

according to the comments by Dima.

 with respect to saturation.