Add gui.Control[HWNDorClassNNorText]; implement gui.Title getter
Gui, Tab -> tabCtrl.UseTab([tabIndexOrName, exactMatch?])
Turn ListView/TreeView/StatusBar functions into methods, see details:

- Removed global_struct::GuiDefaultWindow and 'GuiDefaultWindowValid().
- Removed GuiType::ValidGui(), 'mCurrentListView and 'mCurrentTreeView.
- Removed the LV/TV/SB BIFs from the BIF list
- Made those BIFs accept an additional (C++) parameter to
  identify the control
- Added code to GuiControlType::Invoke() to call the beforementioned BIFs.
- Removed Gui,ListView and Gui,TreeView.