tigefa4u projects Trac

Improve lisibility of admin tests failures by showing expected/actual output using difflib, for all tests.

0.12dev: merged [7819-7824] from 0.11-stable

0.12dev: Merged [7825] from 0.11-stable.

0.11-stable: Added an option `[project] admin_trac_url` to specify a Trac instance to report installation issues when an internal error occurs.

Closes #3722.

Fix one iso8601 unit test, which was not correct anymore after r7823 and add some more.

The `iso8601` format used in some places was wrong, as it displayed always the hour followed by a 'Z', even when the timezone offset was not 0.

Fixes #7921.

Fix r7295, which removed the wrong alternative in the test ... with Genshi 0.5.1 and above required, one should actually '''use''' the cStringIO memory optimization.

Close the attachment file before notifying listeners about the added attachment.

This facilitates the work for some plugins that need to reopen the file.
Patch by anatoly techtonik, thanks!

Closes #7978.

Fix css style for headers within a wiki page, as the current rules didn't play well with embedded divs.

Closes #7970.

Add a hint for saving the email or username in the preferences.

Closes #8000.