[gnome-control-center] (16 commits) ...keyboard: add search support

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

Summary of changes:

  dfa01ba... keyboard: expose structures in header (*)
  d940d7b... keyboard: make it a template class (*)
  c4e1ca2... keyboard: show all shortcuts in a single treeview (*)
  d85047d... keyboard: add a group field to CcKeyboardItem (*)
  c1529c3... keyboard: add helper method for user-friendly accelerators (*)
  fd30442... keyboard: show shortcuts in a listbox (*)
  847fe44... keyboard: remove the shortcuts treeview (*)
  a0a1558... keyboard: introduce CcKeyboardShortcutEditor (*)
  70bba2b... keyboard: avoid stray Meta modified (*)
  60b2357... keyboard: move keyboard management code to custom class (*)
  4e50c3c... keyboard: bring back uniqueness check
  376459a... keyboard: add API to track whether a shortcut is default
  1c85479... keyboard: add support to reset shortcuts to their default v
  d0c32c3... keyboard: remove unused code
  7b877bc... keyboard: bring back reverse item management
  ab8721f... keyboard: add search support

(*) This commit already existed in another branch; no separate mail sent