tigefa4u projects Trac

Update copyright year in license.

Applied the icalendar_roadmap_bug_r5887.patch from ticket #5143, contributed by Justin Francis. In addition, I added a call to `apply_ticket_permissions` to restrict the list of tickets that can actually be viewed by the user.

I also took this opportunity to add Justin to the THANKS file, as he also contributed the new milestone interface ITicketGroupStatsProvider (see r4150).

Fix for #5956.

Real errors in trac-admin now fall through to the console. This changes
trac-admin's exit status to 1 for these cases. Updated unit tests accordingly.

Deprecate potentially confusing permission error message. Logs should be
used by administrators to fix permission problems.

use tuple in `datefmt.http_date` since it gets optimized to a `LOAD_CONST` instead of building the list

Testing: merge through r5978, except for r5962, from trunk.

Add the `vulnerability_tickets.py` sample security plugin to deny access to tickets with "security" or "vulnerability" in the `keywords` or `summary` fields.

Testing: CamelCase words in the dictionary are 'rare', but they cause spurious failures. Flatten them.

Testing: Do a basic test to create a new report. All tests PASS.