reset loaded messages counts on new PLC program trasnfer

This fixes the problem that first message from newer PLC program maybe
lost, if it's issued before first PLC log fetching.

Closes #23

[TOPOLOGY]
NetName=None
Nodes=0x01
Node64Present=0x01
Node64Name=micromod
Node64DCFName=PEAK MicroMod.eds
EDSBaseName=eds