[luatex] callbacks in luatex 0.89

[David Carlisle]

Comparing the list of callbacks in luatex 0.89 to those in 0.80 the
changes seem to be

New
- append_to_vlist_filter
- hpack_quality
- process_rule
- show_warning_message

Gone
- pdf_stream_filter_callback
- token_filter


the first three new ones are documented in the manual but not
show_warning_message
the two that have gone are not documented anywhere as a change that I can find.

This came up as a user query about some old code of Taco's on
stackexchange using token_filter

http://tex.stackexchange.com/a/21691/1090

What is the intended replacement for token_filter?

David