This unit manages the event queue.  Widely used utility GenerateSnortEvent() is
in event_wrapper.h.

The event queue has a configurable maximum number of events, which are
preallocated and stored in a linked list.

There are multiple instances of the event queue accessed via a simple
stack.  A push is done before processing a rebuilt packet or rebuilt
payload after which a pop is done.  During that time any wire packet events
are still pending in the event queue higher up the stack.  This ensures
that the events for each packet (wire or rebuilt) are processed separately.

