[libwnck] (16 commits) Non-fast-forward update to branch wip/muktupavels/icons

[Alberts Muktupāvels <muktupavels src gnome org>]

The branch 'wip/muktupavels/icons' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  a29f47a... icon-cache: cache only one size
  777f8e9... class-group: get icons in getters
  58f8117... application: get icons in getters
  04637b3... window: get icons in getters

Commits added to the branch:

  c0cbba4... util: move icon reloading to WnckHandle
  4c45a3b... icon-cache: add invalidation function
  d9357cc... icon-cache: store xwindow in struct
  5061ca5... icon-cache: store also WnckScreen in struct
  6f6854c... icon-cache: remove size parameters from read_icons
  d44f3d3... icon-cache: add functions to get cached icons
  2923894... window: remove icons from private struct
  f62c618... application: remove icons from private struct
  d9e91a9... class-group: get icons in getters
  13f75bc... icon-cache: turn into a GObject
  8bf64ed... icon-cache: add invalidated signal
  5062df2... icon-cache: read icons in getters
  97cadf1... application: load icons only in getters
  f7a750d... window: load icons only in getters
  bf06e7c... icon-cache: make get_icon_invalidated static
  de624e6... icon-cache: make read_icons static