Merge branch '2919_dlg_as_widget'

Merge branch '2919_dlg_as_widget'

* 2919_dlg_as_widget: (57 commits)
  Update po/*.po and po/mc.pot files.
  Internal menu structures are opaque now.
  Add useful macros for widget type cast.
  Unify widget and dialog message handling.
  Remove DLG_WANT_IDLE. Use W_WANT_IDLE instead.
  Rename Dlg_head to WDialog.
  Rename default callbacks of widget and dialog.
  Unify some hotkeys.
  (editcmd_dialog_raw_key_query): adjust sizes and look'n'feel.
  (real_query_recursive): refactoring of dialog.
  "Directory scanning" dialog: adjust look'n'feel.
  Center text in query owerwrite and delete dialogs.
  (query_dialog): center label horizontally.
  Horizontal centering of multi-line label: center each line independently.
  (file_mask_dialog): adjust width calculation.
  (query_dialog): add horizontal line.
  Remove DLG_REVERSE flag.
  Build file operation dialogs in normal order.
  Build find file dialogs in normal order.
  Build "Background jobs" dialog in normal order.
  ...