tigefa4u projects Trac

Add retargeting of open tickets when closing a milestone. Closes #2743.

Added support for a global plugins directory, as described in #2638. Unlike the
environment plugins directory, plugins in this location will not be
automatically enabled.

WebAdmin: Add support for `neo_cs.CS` objects as admin page templates.

In case of exceptions raised early during the processing of a request, show at least the traceback as plaintext, instead of only the exception value.

Pass req through to post request filter method.

Make the output of [wiki:TracAdmin trac-admin] more readable on small terminals. Fixes #2496.

Slightly clarify [wiki:TracStandalone tracd] command line argument, so that the project directory doesn't get confused with the project name, as suggested in #3218

Don't truncate headings, which was done by mistake in r3353. Fixes #3225.

''Reply'' to ticket changes feature added.

* Added ''permalinks'' to ticket changes, using the same look and feel
as those for Wiki section headings.
Note that those permalinks are now also visible when using IExplorer.
* Added inlined ''Reply'' button for each permanent change;
when ''replying'' to a change, the comment associated to the
replied-to change is simply copied and quoted in the comment
textarea. A subsequent change is then recorded to have been
''in reply to'' the former change, enabling some kind of threading
of the comments.
* A permanent change correspond to a modification of the ticket;
ticket changes due to attachments are qualified as non-permanent changes,
as in the current way things work, this kind of change can come and go
(e.g. when the attachment is replaced or deleted)
* there's a new `comment:` link resolver:
- referring to change `n` in the same ticket: `comment:n`
- referring to change `m` in ticket `xyz`: `comment🎫xyz:`
(similar to the `attachment:` link resolver)

Fix for request post processor missing argument.