channel unit test added

added unit test for LSC, non-blocking, read from empty  - should throw
DataNotAvailable
LSMNothing removed, LSC can now be closed

previously LSC did not differ between close/failed and close/OK. It does
now
added enable, disable for counters
instrumentation: exception names refactored
added snapshots and monitors
monitor API refactored
InstrumentationManager now a monitor