ENH: use dictionary::readEntry for detection of input errors (#762, #1033)

- instead of   dict.lookup(name) >> val;
  can use      dict.readEntry(name, val);

  for checking of input token sizes.
  This helps catch certain types of input errors:

  {

      key1 ;                // <- Missing value
      key2 1234             // <- Missing ';' terminator
      key3 val;
  }

STYLE: readIfPresent() instead of 'if found ...' in a few more places.

applications/utilities/preProcessing/mapFieldsPar/mapFieldsPar.C

@@ -313,8 +313,8 @@ int main(int argc, char *argv[])
             )
         );
 
-        mapFieldsDict.lookup("patchMap") >> patchMap;
-        mapFieldsDict.lookup("cuttingPatches") >>  cuttingPatches;
+        mapFieldsDict.readEntry("patchMap", patchMap);
+        mapFieldsDict.readEntry("cuttingPatches", cuttingPatches);
     }
 
     #include "setTimeIndex.H"