writeFileAccumulator contents cleared on errors, nack or ack timeout
memcpy used to transfer data to request message buffer

- You can now cancel parameter change
- Tablete friendly

Also removes qextserialport

Dang, the whole idea is to minimize updates and I forgot to remove my 10Hz test. It's supposed to be 2Hz.

Only QtLocation based mapping supported in future

Will be replaced by Qml + FactSystem tool widget support