[eclipse-pmc] SWT API request: Missing typed listeners

[Grant Gayed <Grant_Gayed@xxxxxxxxxx>]

GOALS/BENEFITS:
- improve api consistency
- increase the visibility of these events,
since some clients assume that typed events are the only types of events
that exist

CORRESPONDING BUG: 
"Missing TypedListeners": https://bugs.eclipse.org/bugs/show_bug.cgi?id=81334
-> proposed patch in report: https://bugs.eclipse.org/bugs/attachment.cgi?id=61001
(note that the four new methods in Control would be copied exactly as-is
to the Control class on each supported platform)

RISK: 
- low, it's new api whose form duplicates
that of many other instances that have been in swt forever

PERFORMANCE IMPACTS: 
- none