Restricted linking to the needed boost lib only.
Removed unusable constructor.

The constructor does not allocate memory. Furthermore it is not possible to allocate memory later on.
Replaced hardcoded boost libs with CMake variables.
Added new class MatrixSparsityPattern.
Added constructor using MatrixSparsityPattern.
Shared boost libraries are now searched for by default.

To search for static boost libs configure with Boost_USE_STATIC_LIBS=ON
from the command line or as a parameter to ccmake.
Remove unnecessary Sparsity.h include.
Add DenseLinearSystem class.

Uncrustified version of original commit.
Replace valarray with vector in dense LinEqSys.
Replace solution check in TestLinearSystem.

Replace incorrect usage of getSolVec().
Uncrustify TestLinearSystem.cpp.
Add DenseLinearSystem test.
Initialize DenseLinearSystem with 0 upon contruction.
Uncrustify LisLinearSystem.{h,cpp}.
Derive LisLinearSystem from ISystemOfLinearEquations.
Remove setOption() from ISystemOfLinearEquations.

It is not used by DenseLinearSystem.
Remove redundant addSubRHS() for double* sub_vector argument.
Rename private matrix, rhs, and solution for consistency.
Add MatrixType and VectorType template parameters to ISystemOfLinearEquations.
Uncrustify ISystemOfLinearEquations.{h,cpp}.