* Add Parser::incrementExpensiveFunctionCount() and use it in CoreParserFunctions...

* Add Parser::incrementExpensiveFunctionCount() and use it in CoreParserFunctions::getcategorycount(); refactor slightly so that formatRaw is called even for 0 (do any languages format that differently? maybe if they use non-Arabic numerals?).  From bug 12698, by CBM.
* Add a cache so that calling getcategorycount for the same category many times won't stupidly repeat the same query over and over.  Currently an early return avoids incrementing the expensive function count in this case, so technically this makes things *slower*, not faster, but that can be tweaked if anyone cares.