Change number of samples from int16 to uint16, as this should
never be negative. Change timestamp from uint64 to int64, as
negative timestamps may one day be necessary.

The user can now select up to 5 different phase detectors within the same
module, each triggered on one of four different phases. Each can have
its own unique input channel, output channel, and gate. This is a vast
improvement over what we were dealing with beforehand.