tigefa4u projects Trac

WorkFlow:

* Merged log:trunk:2867:2963
* Removed dictionary hacks made redundant by WSGI merge.

* Under [wiki:TracModPython mod_python], you couldn't have multiple headers with the same name (e.g. `Set-Cookie`), which was the cause for #2843. That is now fixed by using `req.headers_out.add()` instead of dict-style assignment.
* Also under mod_python, when using a non-multithreaded MPM, the Trac environment wasn't being reused.
* Minor cleanup of session code.

No need to provide a default value, it's automatically pulled from {{{db_default.py}}}.

Migrated [wiki:TracStandalone tracd] to use the Python {{{optparse}}} module, and moved all the actual code into {{{trac.web.standalone}}}.

Add back support for the [wiki:TracModPython mod_python] option !TracUriRoot which apparently got lost on the WSGI branch.

Fix typo in dispatcher introduced in the WSGI merge.

Properly display source path properties having a dot character in their names

Merged WSGI branch into trunk.

WSGI branch: sync with [source:trunk@...].

WSGI branch: fix CGI error message, some minor cleanup.