tigefa4u projects Trac

Use html utils to format Changeset links. Closes #3166.

TracRevisionLog TracLinks improvements:
* added restricted log range syntax (e.g [3000:3300/sandbox],
the log between 3300 and 3000 concerning the sandbox)
* added InterTrac shorthand syntax for the log ranges
(e.g. [trac 3000:3300] or even [trac 3000:3300/sandbox])

Introduced ''citation'' syntax for the Wiki, e-mail style.
Each leading ">" character introduces a new level of citation.

This reuses most of the machinery introduced previously
for a more robust handling of blockquotes.

However, note that in the case of citations, the ''depth''
of a blockquote corresponds stricly to the number of leading
">" characters.

Follow-up to r3314, use `to_unicode()` instead of `unicode()`, as `text` can actually be some `str` provided by a pre-unicode user macro.

Robust coupling of Wiki lists and Wiki quotes

With [3316], new indent levels are only introduced when they need to be.

However, the implicit relationship that existed between the
indentation level of the lists and the indentation level of the blocks
was lost.

We therefore keep track of the indentation level introduced by
either of them, referred to as "tabstops".

That way, the current indentation is remembered even when
empty lines are introduced for clarity, and the appropriate
indenting is used for quotes following lists or quotes:

{{{
* first level
* second level

A second level quote
}}}

Tab characters are now converted before the line is parsed.

Fixes #124.

More robust parsing and formatting of Wiki lists (#124)

Previously, each indent of 2 spaces would introduce a new indentation level.
This lead to a confusing output in a variety of situations,
especially in changelog style commit messages.

Now, new indent levels are only introduced when they need to be,
i.e. when there's actually a new indented list or paragraph:

{{{
* first level
* second level
- third level

First level
Second level
}}}

Note that a tab character is converted to 8 space characters
before computing the indentation level.

In addition, lists can now also be started using "-" (as this is commonly found
in changelogs as well).

There will be a follow-up changeset focused on the interaction between lists and quotes.

Adding sections to the wiki-tests file.

Added unit test for mixed lists with multi-line items.

Fixed a subtle unicode issue related to string expansion when using an `trac.util.markup.Element` argument.

The result of a string expansion (e.g. `"%s" % text`) is either a `str` object or an `unicode` object, depending on the arguments:
* if there's at least one `unicode` argument, the result will be `unicode`
* otherwise, it will be a `str` object, regardless of the actual type of
the argument __after__ the call to `__str__`.

So in this case, doing `"</p>%s<p>" % text`
when `text` is a `trac.util.markup.Element` object
will result in the `unicode` object returned by
`Fragment.__str__` to be coerced into a `str` object,
which in turn may raise the usual `UnicodeEncodeError` ...

Quick fix for the log TracLinks syntax involving hexa ids: a minimal length is now required if hexa numbers are used.