Provide default AssemblerLib::GlobalSetup ctor.

Compilation fails otherwise with clang-3.3.0, and other compilers.

Fix a compiler warning after merging GaussLedgendre

Merge branch 'move-FemLib-to-OGS' of https://github.com/norihiro-w/ogs into norihiro-w-move-FemLib-to-OGS

Add Gauss quadrature rule in MathLib

Substitute enums using enum classes

Assembler lib2

This reflects that this class can be used otherwise as only for
linear equation system assembly.

Also add a typical setup using GlobalDense matrix and SerialExecutor.

Cleaning up the files and corresponding directories as well as cmake inputs.

It is checking only creation and sizes of the vector and matrix.

Both are independent of each other.