snapshot-29

Menu refactoring

The menu system has been refactored, hopefully this means that the menus
will have improved but it could also mean that I have introduced new
bugs, so be on the look-out.  From the user perspective this refactoring
brings the following changes:

- copy&paste and other "Edit" menu items now work as expected with
  dialogs (such as open/save).
- some menus (such as the "Window" menu) has got some new items
- general menu improvements when no editor window is open
- window-cycling key Cmd-` is no longer hard-coded and can be changed
  with :macmenu command
- ability to access some OS X default Cmd-keys even if menus are
  completely altered (e.g. when starting with "-u NONE")

The last item has the side-effect that it is not possible to remap some
Cmd-keys; the Cmd-keys that are affected by this are exactly those that
appear in the menus when all editor windows are closed.  If this becomes
an issue then I will do something about it.

Other changes:
- QuickLook works with .vim files (patch by Nico Weber)
- insert mode cursor honors the 'rightleft' option
- no more "freezes" during :shell
- no beeping on Cmd-q
- Cmd-w works in full-screen again
- window dimensions properly restored when leaving full-screen when
  "maxvert" is in 'fuoptions'
- support for 'mousehide' option
- latest vim patches and runtime files