Add actions on the selected nodes to the Node menu

[fdb]

The following actions are only available from the context menu:

• Set Rendered
• Rename
• Delete
• Group into Network
• Edit Children
• Help

Where it makes sense, we could also add them to the Node menu in the global menu bar, disabling them when the option is not available.

[techieshark]

+1. I stumbled on this on Mac OS X while following instructions on the subnetworks tutorial which said to "Right-click one of them and choose “group into network” (but right clicking for me just right clicked on one item, deselecting the others). This page had the solution, which is to two-finger tap, but my first thought was to check the menus to perform this aciton.