CONFIG: add additional modules/ directory and Module namespace

- any code placed here should provide Allwmake and Allwclean scripts
  and normally have compilation targets into FOAM_APPBIN, FOAM_LIBBIN

  Since there is no standardize places for sources or applications,
  a simultaneous build of a module's doxygen documentation requires
  a minor bit of manual effort. Add (via symlink) the sources into
  the modules/doc/ directory to have them included in the normal
  OpenFOAM doxygen documentation generation.

  A makelink.example file is provided there as an example.

modules/doc/makelink.example

@@ -0,0 +1,11 @@
+#!/bin/sh
+cd ${0%/*} || exit 1
+
+# Manually create doxygen links for module documentation
+
+for dir in cfmesh/meshLibrary
+do
+    [ -d "../$dir" ] && ln -svf ../$dir ${dir##*/}
+done
+
+#------------------------------------------------------------------------------