[merge request] Doc etc.

[Teika Kazura <teika lavabit com>]

Hi, please merge my branch. It includes
* Doc, mainly "windows" chapter. Difference between
  'window-wants-input-p' and 'window-really-wants-input-p' is
  described. Function 'display-window' is documented.
* Dropped the edition number and the date of last change from info.
  They're no so much meaningful now.
* Long unsupported option 'ignore-window-input-hint' is deleted.

Regards,
Teika (Teika kazura)