Added TODO
BBCodeMonkey: preparing for the possibility of adding rules via the custom syntax
Fixed variable name. No functional change intended
TagProcessingTest: test the tag that's storred in the logs
Changed the class used for testing autoloading, as Tag is loaded while PHPUnit executes the dataProvider methods
TagProcessing: added a log entry for disallowed tags
TagStack: add a warning to the logs when a disabled tag is used