Solution node context menu offers rename project incorrectly

[Gavin-Williams]

[minor issue]

When I bring up the solution node context menu, there is an option to rename project. It isn't a project, it's a solution. The menu item should be changed to just 'rename' - that would resolve the inconsistency.

[GeorgRottensteiner]

As described in #102, there is actually no solution node. So "rename project" would be the correct term.

I'm now thinking to add a solution node, to keep consistent (and it would make accessing Solution options less awkward)