Reimplement init/deinit API of widgets.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Reimplement find widget functions to support groups.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
(widget_is_active): reimplement to support groups

...and related changes.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
W_TOP_SELECT: new widget option to place widget on top of other widgets in group.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Join widget_state_t and dlg_state_t.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Start reimplementation of widget selection.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Use WIDGET_STATE_ACTIVE state in menu.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Optimization of menubar activization.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
WIDGET_STATE_FOCUSED: add new state and handle it.

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

Use MSG_FOCUS and parm == 1 to focus widget.
Use MSG_FOCUS and parm == 0 to unfocus widget.

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