tigefa4u projects Trac

A few enhancements and bug fixes for labelled TracLinks:
* don't strip the namespace of external links if no label is given (fixes #2029)
* labels can be quoted with '...' or "..." (identical to the way the target can be quoted)
* both target and label can be omitted (links like `[search:]` are possible)

If an error occured sending a "pretty" error page, and sending a plain error page results in an `IOError`, just ignore the error. Closes #1999.

Fix some typos that slipped into [2265]. Sorry.

* Fix formatting of non-ASCII dates by using the `to_utf8()` from `format_date()`. Closes #2089.
* Clean up temporary files when executing a command through `NaivePopen` fails unexpectedly. Closes #2079.
* Remove obsolete code from `trac.util`.

* Fix rendering of trailing unchanged blocks in diffs. Closes #2090.
* Fix line numbers, column labelling and chunk separators in `PatchRenderer`. Closes #1985 and #2012.

Make `hotcopy` compatible with database drivers other than PySQLite < 2. Fixes #2016.

Minor simplification of `%s` to `?` mapping in PySQLite2 adapter.

Fix category of revision log RSS feeds.

Set some platform-dependent I/O mode flags needed in CGI mode (fixes #2066 and #2052)

* The `PageOutline` now supports specifying a range of heading levels to include in the outline, as opposed to just the maximum depth. See the docstring of the macro for details.
* Documentation for `PageOutline` and `Image` macro improved.