Context menu: fix note groups getting 'stuck' or not updating properly Prior to 8013f4c, these weren't issues due to the menu always being rebuilt before opening the context menu. Now that it isn't being rebuilt, the menu items weren't being deselected when another group was selected from the context menu, and they weren't being updated at all when the current group was changed through the manager. This commit fixes both of those issues by adding the radio items to a group as they should have been from the start, and making sure the correct item is selected whenever the current group setting is changed. Fixes #166
