tigefa4u projects Trac

WikiContext improvements: introduce Context subclasses, corresponding to Wiki (r4566) and Ticket (r4569) resources.

Also clean-up trac.wiki.api by removing the old Context from there (now in trac.context).

Backport r4735, the trac.context doctest fixes.

PermissionPolicy: merge with log:trunk@...:4734, plus trac.context doctests fixes

(No more trac.resource, see trac.context instead)

WikiContext improvements: gradual move from the Wiki concern toward a more generic resource descriptor concern.

A Context at this point is still:
- a way to specify ''what'' Trac resource is being accessed. This is the ''resource descriptor'' side, the ''input'' details.
- a way to specify ''how'' that Trac resource is being accessed. This is the ''rendering context'' side, the ''output'' details.

This also brings in some changes done in the [PermissionPolicy security] branch, focusing for this changeset on the r4666 fixes.

Small fix for r4728, needed when `--pidfile` is not specified.

PermissionPolicy: merged log:trunk@...

SpamFilter (captcha): Merged log:sandbox/spam-filter@...:4508

Ported r4728:4729 to 0.10-stable (re #4531)

revert accidental changes in r4728 (I wish svn reviewed my changes before committing like darcs :(

also absolutize `--pidfile` tracd option (re #4531) and raise an error when trying to use relative paths with both `--auto-reload` and `--daemonize`