Added a faster early exit for waitForCleared() and waitForSet() in booleanSemaphore
Used booleanSemaphore to do the waiting in GanymedeXMLSession.getNextErrChunk

This should speed up getNextErrChunk as fast as possible at the end of XML
processing.
Slowed down the blocking spin in GanymedeXMLSession.getNextErrChunk to ease the load on the server a bit.