* Added Profiler::isStub() to check if we are using a stub profiler, instead of check...

* Added Profiler::isStub() to check if we are using a stub profiler, instead of checking whether $wgProfiler is set
* Replaced wfProfileClose() and wfGetProfilingOutput() by direct calls to the Profiler instance and removed them, no uses in extensions
* Also removed useless params from Profiler::getOutput() call in wfLogProfilingData()
* Only generate profiling output if it'll be used; introduced Profiler::logData() that saves profiling data (database, udp, ...) to separate it from output generation
* Removed unused Profiler::getCaller(), not used at all, and we have wfGetCaller() that does the same thing