ENH: improve separation of OpenFOAM and ThirdParty mpi-libraries

- drop FOAM_MPI_LIBBIN variable in favour of FOAM_MPI from which
  two different locations can be determined.

  Previously there was something like this:

      FOAM_MPI_LIBBIN = $FOAM_LIBBIN/openmpi-1.5.1

  We now instead determine the locations from the FOAM_MPI directly:

      FOAM_MPI=openmpi-1.5.1

          $FOAM_LIBBIN/$FOAM_MPI     -> OpenFOAM  mpi-related
          $FOAM_EXT_LIBBIN/$FOAM_MPI -> ThirdPary mpi-related

ENH: relocate ParaView libraries and plugins back under FOAM_LIBBIN

- as discussed with Mattijs

src/parallel/decompose/Allwmake

@@ -1,7 +1,7 @@
 #!/bin/sh
 cd ${0%/*} || exit 1    # run from this directory
 
-# get SCOTCH_VERSION, SCOTCH_ARCH_PATH, SCOTCH_MPI_INCLUDE
+# get SCOTCH_VERSION, SCOTCH_ARCH_PATH
 settings=`$WM_PROJECT_DIR/bin/foamEtcFile apps/scotch/bashrc`
 if [ -f "$settings" ]
 then
@@ -19,7 +19,7 @@ wmakeLnInclude decompositionMethods
 wmake libso scotchDecomp
 wmake libso metisDecomp
 
-if [ -d "$FOAM_MPI_LIBBIN" ]
+if [ -d "$FOAM_LIBBIN/$FOAM_MPI" ]
 then
 (
     WM_OPTIONS=${WM_OPTIONS}$WM_MPLIB

src/parallel/decompose/metisDecomp/Make/files

@@ -1,3 +1,3 @@
 metisDecomp.C
 
-LIB = $(FOAM_EXT_LIBBIN)/libmetisDecomp
+LIB = $(FOAM_LIBBIN)/libmetisDecomp

src/parallel/decompose/ptscotchDecomp/Make/files

@@ -1,3 +1,3 @@
 ptscotchDecomp.C
 
-LIB = $(FOAM_MPI_LIBBIN)/libptscotchDecomp
+LIB = $(FOAM_LIBBIN)/$(FOAM_MPI)/libptscotchDecomp

src/parallel/decompose/ptscotchDecomp/Make/options

@@ -3,9 +3,9 @@ sinclude $(RULES)/mplib$(WM_MPLIB)
 
 EXE_INC = \
     $(PFLAGS) $(PINC) \
-    -I$(SCOTCH_MPI_INCLUDE) \
+    -I$(SCOTCH_ARCH_PATH)/include/$(FOAM_MPI) \
     -I/usr/include/scotch \
     -I../decompositionMethods/lnInclude
 
 LIB_LIBS = \
-    -L$(FOAM_MPI_LIBBIN) -lptscotch -lptscotcherrexit -lrt
+    -L$(FOAM_EXT_LIBBIN)/$(FOAM_MPI) -lptscotch -lptscotcherrexit -lrt

src/parallel/decompose/scotchDecomp/Make/files

@@ -1,3 +1,3 @@
 scotchDecomp.C
 
-LIB = $(FOAM_EXT_LIBBIN)/libscotchDecomp
+LIB = $(FOAM_LIBBIN)/libscotchDecomp