evoque template support via contrib.template

[foxbunny]

I've used evoque templating system a bit, and it looks really good. The contrib.template could use a render_evoque for this templating system. Patch to do this is attached.

More info about evoque:

http://evoque.gizmojo.org/

"Evoque is a full-featured generic text templating system for python using a simple $-substitution syntax and providing support for flow control, nested templates, overlays, inter-template addressing and invocation, cache management, arbitrary python expressions, all python % operator formatting, restricted execution, automatic cross-site scripting protection, advanced encoding guessing algorithm, and more."

[foxbunny (bg-branko)]

I've found a better solution than the original patch. It allows render_evoque to pick up a file with any extension, the way Templetor behaves.