* Renamed the enum epicsEventWaitStatus to epicsEventStatus
* Defined epicsEventWaitStatus as a macro for epicsEventStatus
* Renamed epicsEventWaitOk to epicsEventOk
* Renamed epicsEventWaitError to epicsEventError
* Defined epicsEventWaitOK and epicsEventWaitError as macros
* Added epicsEventTrigger(id) which triggers an event and returns OK or an
error status if the underlying OS primitives report an error
* Added epicsEventMustTrigger(id) which halts on error
* Defined epicsEventSignal(id) as a macro for epicsEventMustTrigger(id)
* Added a new C++ method epicsEvent::trigger() which throws an
epicsEvent::invalidSemaphore in the event of an error
* epicsEvent::signal() makes an inline call to epicsEvent::trigger()
* epicsEventWait() and epicsEventWaitWithTimeout() now return an error
status if the underlying OS primitives report an error
* All the epicsEventMust...() routines are now implemented in the common
libCom/osi/epicsEvent.cpp source file, and call cantProceed() instead of
mis-using assert()
* Implemented epicsEventShow() on Posix
