Record time value, by requiring it
Float first then the two integer types
Remove recorder_id from data item struct

The payload for a data item should not need to carry the recorder
id. Adding it to each item will just add a lot of extra data. So instead
the payload frame, i.e. the initial frame in a message should carry that
information.

This also removes the necessity to mask a single char for squeezing both
type and length into the same variable. (Perhaps some other bit masking
technique would have been better but now it is not necessary at all).
Comment out thread sleeping and unnecessary data reading