Automatically append note about version to wiki documentation

[Ryan J Ollos]

In the documentation for 0.12/, Current (1.0) and [[1.1/] we add note at the top of the page. For the 1.1 documentation the note consists of the following markup:

{{{#!box note
This page documents the **1.1dev** version of Trac. See [[wiki:/TracReports]] if you need the previous version.
}}}

This page documents the 1.1dev version of Trac. See TracReports if you need the previous version.

I was thinking it would be easy to write a simple plugin implement IRequestFilter that inspected path_info and used the list of default pages to determine which pages should have the message prefixed, and then generated the message by interpolating a string template. We would want to ignore at least WikiStart, but that could be a configurable parameter.

This could be a single-file plugin, or we could make an EdgewallPlugin and extend it with other custom features in the future.

I hope to look into this after the release.