Possible subtasks
- Parser.php API is appropriate for long-term removal of legacy parser, final removal of tidy, integration of parserTests frameworks (NOTE: not all of these might get done)
- Docs updated to reflect installation of Parsoid/PHP
- Ensure VE works with Parsoid out of the box (without RESTBase). This requires updates to VirtualRestService code in MediaWiki core to have VE talk to Parsoid via the internal library API instead of a HTTP API