tigefa4u projects Trac

fix test errors due to `EnvironmentStub` missing the `systeminfo` property

sqlalchemy: merge with source:trunk@...

PageTemplates: follow-up to r3881, doing some cleanup suggested by coderanger and matt_good.

note why use of `keys()` is intentional as opposed to normally preferring `iterkeys()`

Improved internal error reporting:

Internal errors are eith indicative of a problem with the Trac installation or a bug in Trac itself.
In both cases, the Trac admnistrator must be the first informed, as he's the most adequate person to either fix the installation issue or to relay the bug report to the TracTeam.

This is why upon internal errors, "normal" users will now be told to contact their local Trac administrator.
A new `[project]` setting, ''admin'', can be used to define a mail contact. If this contact information is not defined, a button for creating a ticket on the local Trac will added instead of the mailto: link.

When someone with the TRAC_ADMIN permission hits an internal error, however, he will have the full stacktrace information as before, plus some system information obtained from the new `self.env.systeminfo` dictionary.
In addition, he will be advised to ''search'' on Trac's Trac for a similar issue, and will have the possibility to create a ticket directly on t.e.o, with all the information we usually ask for.

The ''Create'' button will only prepare a new ticket (''preview'' mode). That way, the description can be further edited and other ticket fields can be set before submitting.

''This change could eventually be backported to [milestone:0.10.1]''

Added basic documentation for the PageTemplates feature.

TracWiki: implement simple PageTemplates (#962)

The default content for a new wiki page can be chosen from a list of page templates.

This list is made up from the wiki pages having a name starting with ''PageTemplates/''.
The initial content of a new page will simply be the content of the chosen template page, or a blank page if the special ''(blank page)'' entry is selected. When there's actually no wiki pages matching that prefix, the initial content will always be the blank page and the list selector will not be shown (i.e. this matches the behavior we had up to now).

To create a new template, simply create a new page having a name starting with ''PageTemplates/''.

(Hint: one could even create a ''!PageTemplates/Template'' for facilitating the creation of new templates!)

TracMercurial: experimental support for the extended changelog format (we display the extra changeset properties)

TracMercurial: compatibility fix for the new extended changelog information.

Thanks to Shun-ichi GOTO for the report and the fix.

MercurialPlugin: compatibility fix for post-0.9.1 Mercurial versions (>= [hg abd9a05fca0b]).

Thanks to Georg for reporting this and providing a fix.