regression test instructions:

   ../../bin/<arch>/testManager st.cmd
   testManagerAllPorts temp
   exit

   then on host
   diff temp test20050725

   there should be no differences
   NOT TRUE: May be subtle timing diffs if workstation is busy

NOTES:

testManager.c has epicsThreadSleep in many of the callbacks.
This, of course, violates the rule that callbacks should not
block except because of calling interface methods. The
epicsThreadSleep calls are used to cause particlar states in asynManager

The test tests two features of asynManager:

1) blockProcessCallback/unblockProcessCallback
2) cancelRequest.
