We set AM/PM label on format change in init(),
but we shall not have set the time in the editor
in init() which results in wrong label if the time
is PM.
Fix it by updating clock label after time changes
This is only the bare minimum to make everything under panels/common
build. Since these widgets are used by the main window, port them
first.
CcTimeEntry was particularly hard to port. That's because GtkEntry
is a final class now. Overall, though, I'm happy with how it turned
out to be - much cleaner, less code, more obvious.