Roll back r43377, r43379 "Factored wfInvokeFancyCallback() out of wfRunHooks(). Allow...

Roll back r43377, r43379 "Factored wfInvokeFancyCallback() out of wfRunHooks(). Allows flexible dynamic invocation to be used in other contexts." / "Renamed the new wfInvokeFancyCallback to simply wfInvoke."

Breaks existing hooks including core language converters:

Notice: Undefined variable: event in /Library/WebServer/Documents/trunk/includes/Hooks.php on line 61
Warning: call_user_func_array(): First argument is expected to be a valid callback, 'ZhConverter::on' was given in /Library/WebServer/Documents/trunk/includes/Hooks.php on line 119
Notice: Undefined variable: args in /Library/WebServer/Documents/trunk/includes/Hooks.php on line 80
Notice: Undefined variable: event in /Library/WebServer/Documents/trunk/includes/Hooks.php on line 61
Detected bug in an extension! Hook ZhConverter::on failed to return a value; should return true to continue hook processing or false to abort.
Backtrace:
#0 /Library/WebServer/Documents/trunk/includes/Article.php(1684): wfRunHooks('ArticleSaveComp...', Array)
#1 /Library/WebServer/Documents/trunk/includes/Article.php(1354): Article->doEdit('Article for spe...', '', 97)
#2 /Library/WebServer/Documents/trunk/maintenance/parserTests.inc(998): Article->insertNewArticle('Article for spe...', '', false, false)
#3 /Library/WebServer/Documents/trunk/maintenance/parserTests.inc(307): ParserTest->addArticle('Xyzzyx', 'Article for spe...', 5168)
#4 /Library/WebServer/Documents/trunk/maintenance/parserTests.inc(273): ParserTest->runFile('/Library/WebSer...')
#5 /Library/WebServer/Documents/trunk/maintenance/parserTests.php(73): ParserTest->runTestsFromFiles(Array)
#6 {main}