orbtk: new example code `mgs_handler`
orbtk: new example code `mgs_handler`

This example illustrates the usage of massage handling between
individual widgets (here: SenderView and ReceiverView).

* msg_handler: the controlling window.
* sender: handle view and state to handle message sending.
* receiver: handle view and state to react when message are passed over.

Signed-off-by: Ralf Zerres <a55c5beace021459791f5070a9a90148cd697b8f@networkx.de>

redox-os/orbtk