Added a couple of Unity helper methods:
PollSystemState:
Asynchronously wait for a specified system state within a coroutine
CurrentSampleOffset
Due to how BCI2000 handles data (signal, events) in blocks, it is not possible to get the most recently captured sample. In lieu of this, we instead get the value of the sample exactly one block length after it is collected, so as to normalize the latency.
This should be the final beta release before 2.0.0