Some parser functions, and quite a bunch of stubs of parser functions.

IMPORTANT NOTE: These parser functions are only used by the Parsoid-native template expansion pipeline, which is not the default or used in production. Normally we use API calls into a MediaWiki installation to implement parser functions and other preprocessor functionality. The only use of this code is currently in parserTests, but those tests should probably be marked as PHP-only and any mixed testing moved into separate tests. This means that there is not much point in spending time on implementing more parser functions here.

There are still quite a few missing, see and Instantiated and called by the TemplateHandler extension. Any pf_<prefix> matching a lower-cased template name prefix up to the first colon will override that template.