tigefa4u projects Trac

* Change the configuration for disabling components: instead of a `[disabled_components]` section that lists all components to be disabled, you can now enable/disable components in a `[components]` section. This also means that plugins need to be explicitly enabled for every environment. Closes #2019.
* Support a global `trac.ini` configuration file (by default in `$prefix/share/trac/conf`). Closes #1051. Thanks to Alec Thomas for the patch.

Load plugin eggs from `projenv/plugins` first.

Exclude description field from header in notifications.

Fix the fix in [2331]. Need. Unit. Tests. For. Notification. Code.

Fix formatting of `textarea` type custom ticket fields in email notifications, as well as any field that for some reason has newlines in its value. Closes #2192.

Fix typo in [2329]. Sorry.

Fix some line endings in the ticket notifications mails. Set eol-style of the template to `CRLF`.
Closes #2191. Thanks to Matthijs Kooijman for the patch and suggestions.

Create dev branch for notification refactoring

Dev branch for Matt.

"0 seconds" instead of "0 second"