BUG: _foamAddPath not available when foamPV alias/function is used

STYLE: only use paraview settings when actually available

- this means executing makeParaView prior to building OpenFOAM itself,
  but is consistent with the instructions given by makeParaView,
  and elminates anticipating the source location from the paraview
  config file, which increases the build flexibilty for ThirdParty

etc/config.sh/paraview

@@ -49,6 +49,9 @@
 #         export LD_LIBRARY_PATH=$ParaView_DIR/lib/paraview-5.2:$LD_LIBRARY_PATH
 #         unset ParaView_VERSION        # avoid using ThirdParty settings
 #
+# Note
+#     When _foamAddLib is unset (eg, called from makeParaView or from foamPV):
+#         - the ParaView_VERSION variable is retained.
 #------------------------------------------------------------------------------
 
 ParaView_VERSION=5.2.0
@@ -70,7 +73,8 @@ cleaned=$($WM_PROJECT_DIR/bin/foamCleanPath "$PATH" \
 cmake=$WM_THIRD_PARTY_DIR/platforms/$WM_ARCH$WM_COMPILER/$cmake_version
 if [ -r $cmake/bin/cmake ]
 then
-    _foamAddPath $cmake/bin
+    # _foamAddPath not available when foamPV function is used
+    PATH=$cmake/bin:$PATH
 fi
 
 # Evaluate command-line parameters for ParaView
@@ -112,12 +116,11 @@ then
 
     pvName=ParaView-$ParaView_VERSION
     pvMajor=paraview-$ParaView_MAJOR
-    pvSrcDir=$WM_THIRD_PARTY_DIR/$pvName
 
     export ParaView_DIR=$WM_THIRD_PARTY_DIR/platforms/$WM_ARCH$WM_COMPILER/$pvName
 
     # Set paths if binaries or source are present
-    if [ -r $ParaView_DIR -o -r $pvSrcDir ]
+    if [ -r $ParaView_DIR ]
     then
         pvLibDir=$ParaView_DIR/lib/$pvMajor
         pvPython=$ParaView_DIR/Utilities/VTKPythonWrapping
@@ -147,13 +150,24 @@ then
             echo "    PV_PLUGIN_PATH       : $PV_PLUGIN_PATH"
         fi
     else
+        if [ "$FOAM_VERBOSE" -a "$PS1" ]
+        then
+            echo "No paraview found"
+            echo "    ParaView_DIR         : $ParaView_DIR"
+        fi
+
         unset ParaView_DIR ParaView_INCLUDE_DIR PV_PLUGIN_PATH
     fi
 
 fi
 
 unset -f _foamParaviewEval
-unset cleaned cmake cmake_version pvName pvMajor pvSrcDir pvLibDir pvPython
-unset ParaView_VERSION ParaView_MAJOR
+unset cleaned cmake cmake_version pvName pvMajor pvLibDir pvPython
+unset ParaView_MAJOR
+
+if type _foamAddLib > /dev/null 2>&1    # normal sourcing
+then
+    unset ParaView_VERSION
+fi
 
 #------------------------------------------------------------------------------