ENH: initial revamp of faMesh to improve modularity (#2084)

- improved separation of patch creation that is also parallel-aware,
  which now allows creation in parallel

- memory-safe use of PtrList for adding patches, with a more generalized
  faPatchData helper

- use uindirectPrimitivePatch instead of indirectPrimitivePatch
  for internal patch handling.

- align boundary methods with polyMesh equivalents

- system/faMeshDefinition instead of constant/faMesh/faMeshDefinition
  as per blockMesh convention. Easier to manage definitions, easier
  for cleanup.

- drop inheritence from GeoMesh.

applications/utilities/postProcessing/dataConversion/foamToVTK/writeAreaFields.H

@@ -39,7 +39,7 @@ SourceFiles
 #define writeAreaFields_H
 
 #include "readFields.H"
-#include "foamVtkIndPatchGeoFieldsWriter.H"
+#include "foamVtkUIndPatchGeoFieldsWriter.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -47,7 +47,7 @@ namespace Foam
 {
 
 // Writer type for finite-area mesh + fields
-typedef vtk::indirectPatchGeoFieldsWriter vtkWriterType_areaMesh;
+typedef vtk::uindirectPatchGeoFieldsWriter vtkWriterType_areaMesh;
 
 template<class GeoField>
 bool writeAreaField