Translate Wiki Links to URLs

Translate Wiki Links to URLs

Wiki links (`NameOfWikiPage`) in bugs on Trac should be converted to URLs. As URLs they are useful in Launchpad too.

The relationship between Wiki names and URLs seems to be a simple text replacement operation. No access to the repository seems necessary.

This idea can not be implemented naively. A naive implementation would insert
large amounts of text (an URL) for every camel case word. There must either be
a way to mark words that should be converted, or a smart algorithm that does
the conversion only when it is appropriate.

Three basic strategies:

 * Mark links with rectangular brackets (`[NameOfWikiPage]`). To reduce the risk
   of colliding with Python source code, demand whitespace around the brackets,
   like it was done for bug-links. This also allows escaping the whole
   construction.

 * Structure it clearly as a text replacement command. For example
   `[@URL NameOfWikiPage]`. This could easily be expanded to converting bug
   links: `[@URL bug #123]`

 * Test if there is in fact a Wiki page at the URL before inserting it. To
   reduce network traffic store URL where pages really exist. The link must be
   the last word in a short line, maybe 40 characters are permissible before
   the link. Demand mandatory whitespace around the camel case word, to reduce
   the risk of colliding with Python source code.

See also:
bug #934724 (Translate bug-links)