bug#7303: Suggestion: Move minor mode menus to one common top-level submenu

[Lennart Borgman]

I saw Jonas Bernoulli posted a similar question (for the modeline) here:

  http://www.emacswiki.org/emacs/ModeLineMinorModeMenu

I suggest we move all minor mode to one common top-level submenu for
two reasons:

- It takes less space in the menu bar.
- The distinction between minor and major modes becomes more clear.

This submenu could also preferably be ordered by local and global minor modes.