[PL] GW: Add LocalAssemblerData skeleton.
WIP ShapeMatrixPolicy smth.
[PL] GW: Add LocalDataInitializer.

This adds a mapping from element types to the
corresponding shape functions. The latter are
passed as a template parameter to the
LocalAssemblerData.
[PL] GW: Add local assembler initialization.
[PL] GW: Add IntegrationPolicy and order to LAsm.
[PL] GW: Add IntegrationPolicy, order to LDataInit.
[PL] GW: Pass integration types from process to LA.
WIP. Mainly Eigen matrices in shape_matrices array.
[PL] GW: Create FemElement in LAData::init();
[PL] GW: Initialize shape matrices in local asms.
Fill assemble()
[PL] Add global assembler to GroundwaterFlowProcess.
[PL] Execute global assembler on local assemblers.
NOT WORKING. Add getLocalMatrix/Vector to GWFP.
[PL] Pass  GlobalMatrix/Vector types to local assembler.
[ML] Remove size check, because eigen hos no getNRows()

Maybe we should choose different interface instead.
[T] Add GlobalMatrix/Vector to SteadyDiffusion2D example.
debug A.
md: enable parsing of processes' configs.
[T] Save local_to_global_map.

Otherwise there is a reference to temporary.