Workspaces and Universal Source Directory

Jason originally proposed the concept of a "universal source directory" - a layout known to Maven that would allow Maven and plugins to find checkout source code in a uniform way, so that if you work in that particular layout, you can more effeciently work across projects.

We have started to implement some a minor feature of this:

I would like to generalise that, to a "workspace definition". The default workspace will match the originally proposed universal source directory.

Requirements:

This will aid a lot in overcoming issues we have with SVN: instead of checking out from one location to get everything, you let the workspace file pick out the pieces you need and lay it out in the expected way. Multiple workspaces could configure the same sources in different ways (eg to flip to a development version of X).