functionObjects: Renamed dictionary entry 'functionObjectLibs' -> 'libs'

This changes simplifies the specification of functionObjects in
controlDict and is consistent with the 'libs' option in controlDict to
load special solver libraries.

Support for the old 'functionObjectLibs' name is supported for backward compatibility.

src/OpenFOAM/db/functionObjects/writeFiles/writeFiles.H

@@ -74,9 +74,6 @@ protected:
         //- Create the output file
         virtual void createFiles();
 
-        //- Write function
-        virtual void write();
-
         //- Reset the list of names from a wordList
         virtual void resetNames(const wordList& names);
 
@@ -130,6 +127,9 @@ public:
 
         //- Return file 'i'
         OFstream& file(const label i);
+
+        //- Write function
+        virtual bool write(const bool postProcess = false);
 };