[PL] GroundwaterFlow.h -> GroundwaterFlowProcess.h.
Merge pull request #474 from TomFischer/RenameGroundwaterFlowProcess

[PL] GroundwaterFlow.h -> GroundwaterFlowProcess.h.
Disabled warning C4996 on MSVC.

This warning appears in std::fill_n and can be ignored.
Merge pull request #475 from bilke/disable-c4996

Disable warning C4996 on MSVC
Use a relative path to precompiled VTK.

Related to #469.