Write a Level II register to the 32.bit register space

 Care should be taken not to write to much data at the same time as there may be nodes
 that can't handle a full 512 byte frame. Better to seperate srite requests in bunches
 of 100 bytes or so.

 Also be aware that a node may send several read/write response events to fullfil a write request.
 
 | Byte       | Description                                      | 
 | ----       | -----------                                      | 
 | Byte 0-15  | Contains the GUID of the target node (MSB->LSB). | 
 | Byte 16-19 | Register to write (or start index), (MSB->LSB).  | 
 | Byte 20…   | Data to write to register(s) (max 512-16-4 bytes).  | 


