#479 No separate PD and pull/reply sequence counters in callbacks

[Manuel Borelli]

When cyclic PD push traffic and PD pull/reply traffic are used
concurrently with the same ComId, sequence-counter handling is correct
internally. However, the sequence counter provided to the application
callback may be taken from the other flow.

As a result, a callback processing a PD telegram may receive a sequence
counter associated with PP traffic, or vice versa.

This patch keeps the sequence counters used for callback reporting
separate for push (PD) and pull/reply (PR/PP) traffic, so that the
sequence counter reported to the application corresponds to the
processed telegram.