Added new setting pz:apdulog which controls whether APDUs should be

Added new setting pz:apdulog which controls whether APDUs should be
logged for some target(s).
Fixed bug #1252: Using record&offset=.. may hang for a long time.
The problem was that a target did return a record initially but
it failed for later present requests . So it was disconnected at the
time the record&offset= was used.