[merge request] Several minor changes.

[Teika Kazura <teika lavabit com>]

Hi, please merge my branch. It includes:
* Emacs sawfish.el correctly supports let-loop.
  Using it, corrected some indents in the Sawfish source.
* kde-desktop-directories bugfix: Previously, it was impossible
  for users to override it.
* Function & command `popup-window-menu' is renamed to
  `popup-window-ops-menu'. The old name is still supported.
* Doc. Section on "popup menu" is rewritten, and so on.

Best regards,
Teika (Teika kazura)