tigefa4u projects Trac

Add support for `req.args.getlist()` and `req.args.getfirst()` to match the [http://docs.python.org/lib/node472.html higher level interface] of the CGI `FieldStorage` class. Closes #2846.

Moved `TracError` into the `trac.core` module (but importing from `trac.util` should continue to work).

Fixed the definition of a restricted changeset.

The restricted changeset for a path should only show
modified paths that are either:
* exactly the same as the given path,
* the directories above
* the files and folders below the path, if the path is a directory

Before the fix, the restricted changeset for e.g.
`trunk/README` would also show `trunk/README.tracd`,
and conversely.

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