* Removed:
    o the 'Links' tab
    o the 'Forms' tab
    o the 'Security' tab (merged with the 'General' tab)
    o in the 'General' tab:
        - the 'Meta' tree
        - 'Render Mode', 'Cache Source', 'Encoding', 'Expires'
    o in the bottom of the 'Media' tab: 'Expires'

* Added:
    o a 'Feed' tab. For each feed discovered in the page, it displays the
      Address of the feed and its Title. When a feed is selected in the list, it
      is possible to Preview it or to Subscribe if a feed reader has already been
      chosen.

    o a 'Permission' tab. In this tab it is possible to see if the site is
      allowed to load images, open popups, set cookies, install extensions and the
      user is offered the opportunity to change those permissions.

    o in the 'Media' tab:
        - a column 'Size' in the tree view. This displays the size (in KB) of
          each media.
        - a checkbox 'Block images from <hostname>' in the bottom part.

* Various changes:
    o the tabs are similar the tabs used in the new addon manager.

    o the title of the window now contains the URL of the page. This is useful
      because many Page Info windows can be opened at the same time for different
      pages.

    o in the Media list, when a file isn't in the cache (presumably a broken
      url), the row is displayed in gray and italic.

    o in the 'Media' tab, when multiple row are selected in the list, the 'Save As'
      button is still enabled. When multiple images are saved at once, the user is
      asked for a folder in which the images should be saved.


    o the parts of the window which are useless or irrelevant in the current
      context are hidden:

        - in the 'General' tab and the 'Media' tab, when an information is
          unavailable, instead of displaying 'Not specified', 'Unknown'... in gray,
          those lines are hidden.

        - the 'Media' tab is hidden when the media list is empty.

        - the 'Feed' tab is hidden when the feed list is empty.

        - the bottom part of the 'Media' and 'Feed' tabs are hidden if nothing
          is selected in the list or in the case of a multiple selection.
          In that last case, in the 'Media' tab, the 'Save As' button is still visible.

        - the 'Permission' tab is hidden when the current scheme isn't http(s).
          (same thing for the 'Block images from <hostname>' checkbox in the bottom
           of the 'Media' tab)


    o extensibility:

        - extensions can register functions so that they get called by Page
          Info. It was already possible to register functions to be called when Page Info
          loads. Now it is also possible to register functions which will get called:
          for each frame; for each node; when Page Info is closed.

        - it will be easy for extensions to add new permission types in the
          'Permission' tab. That can be used for example by Flashblock or NoScript)

        - it is (and it already was) easy to add tabs to Page Info. For example,
          the 'Feed' and the 'Permission' tabs are overlays. It will be easy to make an
          extension which will add back the 'Links' and the 'Forms' tabs.