Recipe for parser pipelines and -subpipelines, depending on input types.
Token stream transformations to register by type and per phase. The possible ranks for individual transformation registrations are [0,1) (excluding 1.0) for sync01, [1,2) for async12 and [2,3) for sync23.
Should perhaps be moved to MWParserEnvironment, so that all configuration can be found in a single place.
Get a subpipeline (not the top-level one) of a given type.
Generic pipeline creation from the above recipes.