tigefa4u projects Trac

Fixed another unicode problem #3065.

Fixed #3066, Unicode error in SilverCity.

Fixed RSS feed for Timeline with milestone events.

* add macro `[[TracAdminHelp]]` for displaying the docs of trac-admin commands
* remove some of the extra whitespace in trac-admin help output

Allow `bgcolor` attribute in inline HTML. Closes #3254.

Implement ''Previous Change'' and ''Next Change'' links in the Wiki diff view. Closes #3250.

Made the minimal length of the search query configurable

e.g. for Trac installations using mainly the Corean language, where most words are made of 2 characters:
{{{
[search]
min_query_length = 2
}}}

Closes #3264.

Use the more portable `TEMPORARY` sql keyword, instead of `TEMP`. Should fix #3161.

More tweaks to the attachment timeline events: correctly escape filename, author and skip ''by author'' in the title for RSS feed.

Fixed ''Reply'' to ticket description: the ''reporter'' in question here must be the one of the ticket, not the one making the comment...