[gmf-dev] [GMF - API CHANGE] Bugzilla#131723: Moved IListenerContext

[Linda Damus <ldamus@xxxxxxxxxx>]

Description:
Moved IListenerContext from org.eclipse.gmf.runtime.common.ui.services.dnd.internal.core
to org.eclipse.gmf.runtime.common.ui.services.dnd.core.
 This wasn't public before, but it should have been because
clients wanting to use methods from its two public subinterfaces
(IDragListenerContext and IDropListenerContext) will otherwise have access
restriction errors/warnings.

New API Availability: 
In next GMF build.

Old API Removal: 
In next GMF build. 

Tracking:                  
      
Bugzilla#131723

Clients Taken Care of:         
None. 

Other Clients' Action: 
Use the public IListenerContext.