BUG: dangling dictionary reference for expression BCs

- exposed by the new embedded function handling.

  Requires local copies of dictionary content instead
  (similar to coded BCs handling)

BUG: incorrect formatting for expression function output

ENH: simpler copyDict version taking wordList instead of wordRes

- corresponds to the most common use case at the moment

ENH: expression string writeEntry method

- write as verbatim for better readability

src/OpenFOAM/expressions/exprDriver/exprDriverFunctions.C

@@ -188,10 +188,7 @@ static void writeFuncsImpl
                 os.beginBlock(subDictName);
             }
 
-            os.beginBlock(entryName);
-            os.writeEntry("type", (*funcPtr).type());
-            (*funcPtr).writeEntries(os);
-            os.endBlock();
+            (*funcPtr).writeData(os);
         }
     }