WIDGET_STATE_FOCUSED: add new state and handle it.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Add set_state() API to WGroup class.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Use new way to handle WIDGET_STATE_FOCUSED state.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Use mc_event engine to handle focus/unfocus events.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
New group API to select/unselect widget.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Modify update_cursor API to support groups.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Small refactoring of dialog size and position set/change.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
NOT FINISHED: Reimplement set widget size to support groups.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>