tigefa4u projects Trac

In the TracChangeset view, each title of a diff view links to the corresponding restricted changeset, instead of going to the latest revision of that file in the browser.

There are still two other ways to go to the latest revision of that file (from the corresponding '''Files:''' index entry and from the link attached to the newest revision itself, in the diff view itself.

Implements suggestion 2. of #3398.

A batch of minor improvements for the TracTimeline:
- add navigation links (''Previous Period'' / ''Next Period''), with the ''period'' corresponding to the number of days back. Fixes #215.
- show ''Today'' and ''Yesterday'' annotations for the corresponding days. Fixes #2676.
- make the preferences box a bit narrower. Fixes #1013.

Oops, revert debug code that accidently slipped in r4679...

Refactoring of r4677 and take into account special plural of ''copy''

Fix the ''View changes'' form, for files containing the '@' character. Also, normalize changeset.py on using tag instead of html.

In TracTimeline, show the common location for the file entries of changeset events.

This is a follow-up of what r4676 did for the TracChangeset view itself.

The existing TracIni setting `changeset_show_files` is reused:
{{{
[timeline]
changeset_show_files = location
}}}

Implements #3274.

In TracChangeset, show the common location for the file entries.

This will be quite useful for those having deep paths in their repositories, as usually changesets happen below some specific folder in the repository only.
That folder will now be shown as the '''Location:''', and the '''Files:''' section will only contain the paths relative to that Location.

Implements #3549.

Fix a regression introduced by r4668: property changes were not shown in the absence of text diffs.

Tabular/Unified js switch: `substr(5)` was truncating the file names. Fixes #4326.

0.10.4dev: ported r4672 (''improve vcs not supported error message, #4635'')