[A] Check mesh before access in findMeshByName().
[PL] Rename Dirichlet to UniformDirichletBC.

Also clarifies the debug message in ctor.
[PL] Rename numberNodeDOFs to numberOfNodeComponents.
Merge branch 'SkeletonProjectData' into develop
Implementation of IC/BC and ProcessVariable.
[PL] Move BC/IC/ProcessVariable into ProcessLib.
[PL] Add mesh subset to initialize().
[PL] Initialize MeshSubsets and MeshComponentMap.
[PL] Rename mesh_items_all_nodes; items->subset.
[PL] Add destructor for GroundwaterFlowProcess.
[PL] Move mesh_component_map to class variables.

...from the initialize().
Also delete it in the dtor.
[PL] Add createDofMap() in Process.
[PL] Use number of node's DOF in createDOFMap().
[PL] Remove MeshComponentMap include from GW.
[PL] Add dof_map to GroundwaterFlow.
[PL] Empty solve().
[PL] Add empty GroundWaterflowFEM.
Merge branch 'GroundwaterFlow' into develop

Conflicts:
	ProcessLib/Process.h
First OGS simulation main program.
[A] Remove QtXml dependency.