tigefa4u projects Trac

More unicode fixes for the TracChangeset and TracBrowser modules.

* Perform the diffs in unicode. In changeset.py, we convert
the file content to unicode before the diffs are computed.
Should fix #2905 and #2363.
* Clarified some assumptions made in the mimeview component.
Unless stated otherwise, strings should be unicode strings.
This is particularly true for the `preview_to_hdf` method.
Therefore, in browser.py we have to convert to unicode as well.

Both of the above make use of the following:
* a new `Mimeview.to_unicode` method which uses the standard
Mimeview ways to infer the charset from either the content
type or from the content itself
* the above makes use of a new `to_unicode` function in `trac.util`
which always succeeds at producing an unicode string

I also made clear that when using `trac.util.NaivePopen`,
a properly encoded string must be given. I couldn't fully
test the corresponding changes in enscript.py and php.py, yet.

Use `repr` instead of `str` in order to build some unique identifier in the `check_modified` code. This makes it immune to encoding issues. Closes #2963.

Fix some unicode issues for the TracSubversion backend.

* Make conversions to and from Subversion's UTF-8 encoded strings more obvious,
using `_from_svn` and `_to_svn` functions
* The `_to_svn` enables also to clarify and simplify the code related to
scoped repositories
* A few other little fixes were needed in the modules

Note that content related issues are not addressed by this change
(the diff issues of #2905).

Added tests for the `SubversionRepository.previous_rev/next_rev` methods using and additional path argument

Added a file containing accentuated characters to the test svn repository, in preparation for the unicode fixes.

Depend on python2.3-subversion without versioned dependency

WorkFlow:

* Purged last remnants of separate ticket modules.
* Fix for typo in field validation.
* Fix for default values in select/radio controls.

Applied patch for #2951, which adds a {{{add_javascript}}} method to {{{trac.web.chrome}}}.

Make the {{{Markup}}} class assume UTF-8 encoding when it gets passed non-unicode strings (which ideally shouldn't be happening, but hey). Should fix #2905.

Fix the source file syntax highlighting under Emacs by adding an extra `"` character (the one on the line above is not seen by emacs because of the `#` character preceeding it)