rework clone menu

[JChrist]

The current project clone menu requires a "seed node" selection, which, however, is the local httpd URL.
This means that it's only possible to clone projects available to the local httpd, which could very well not be what the user wanted.

At the very least, the seed node selection could change to allow selection of a public node, either from a list of known or "discovered" ones.

And/or allow the user to enter the RID to clone.