Standardized the naming of functions which control the writing of fields etc.

to have the prefix 'write' rather than 'output'

So outputTime() -> writeTime()

but 'outputTime()' is still supported for backward-compatibility.

Also removed the redundant secondary-writing functionality from Time
which has been superseded by the 'writeRegisteredObject' functionObject.

src/postProcessing/functionObjects/field/processorField/postProcessingDict

@@ -28,7 +28,7 @@ functions
         enabled         true;
 
         // When to output the average fields
-        writeControl   outputTime;
+        writeControl   writeTime;
     }
 }