By John M McIntosh johnmci@smalltalkconsulting.com
This class was written to mange the external semaphore table. When I was writing a Socket test server I discovered various race conditions on the access to the externalSemaphore table. This new class uses class side methods to restrict access using a mutex semaphore. It seemed cleaner to deligate the reponsibility here versus adding more code and another class variable to SystemDictionary

Note that in Smalltalk recreateSpecialObjectsArray we still directly play with the table.

	initialize
	initialize

	accessing	top
	clearExternalObjects Clear the array of objects that have been registered for use in non-Smalltalk code.
	externalObjects
	registerExternalObject:
	safelyRegisterExternalObject: Register the given object in the external objects array and return its index. If it is already there, just return its index.
	safelyUnregisterExternalObject: Unregister the given object in the external objects array. Do nothing if it isn't registered. JMM change to return if we clear the element, since it should only appear once in the array
	unregisterExternalObject:

	initialize	top
	initialize Object initialize