tigefa4u projects Trac

vc-refactoring: remove support for displaying additional changeset properties in TracChangeset

vc-refactoring: remove support for shortcuts to branches and tags in the TracBrowser

vc-refactoring: don't use ''abstract'' versioncontrol modules (this will temporarily break the TracMercurial plugin)

vc-refactoring: change the way a backend is specified

Now, the trac.ini has to be setup like this:
{{{
[trac]
repository_type = hg
repository_dir = /usr/local/hg/repos
}}}

By default the `repository_type` is "svn", so nothing will change
for SVN users.

Also, did a few renamings:
* s/IScmBackend/IRepositoryConnector/
* s/ScmBackendManager/RepositoryManager/

Some additional documentation for the `IWikiSyntaxProvider` methods.

The regular expressions of the wiki parser are now operating
on the ''raw'' text, which has not been HTML-escaped.
There's simply one more regular expression which does the
HTML escaping as part of the wiki processing.
This has two advantages:
* no need to unescape again, in several circumstances
* simple regular expressions can be built to handle the "&" character

The latter enables us to fix #2455.

On the other hand, care must be taken by the various _formatter methods
to correctly HTML escape the matched text groups.

Follow-up to r2500, forgot to remove the ";" character when replacing " by `"`

Follow-up to r2413, the collapsing of block into `[...]`
done by the OnelinerFormatter is now done without using a regexp.

The regexp did use negative lookahead expressions which crashed
when the input was too big. Closes #2468.

Ported [2640] to 0.9-stable

Fixed formatting of TracLinks starting but not ending with quotes (problem discovered and discussed in ticket #2468)