Rest todos for 1.6

[Teika Kazura]

Rest todos for me by 1.6 release:

* Viewport leftovers. (Rename viewport-offset-pixel, and unify
  window-{absolute,relative}-position.) Since Jeremy seems busy, I'll
  do it. Planned to submit it by 15 Tue.
* Doc entry "recompile sawfish-pager".

Regards,
Teika (Teika kazura)