Double check eventmarker trimming for user-aborted trials.

[ted-hou]

The current way it works is: event markers received from Arduino are stored to a buffer. Whenever a result code is received, that buffer is cleared and its contents transfered to ArduinoConnection.EventMarkers.

User triggered aborts will also clear the buffer. But if user aborts after a result code is returned, some unwanted data is still saved.

Resolving this would require changing arduino code through one of the following:

• Delay result code transmission until end of trial.
• Have a dedicated event marker (like 0) to signal end of trial. Not recommended because 1) Would cause backwards-compatibility issues with older data, and 2) this would impose further restrictions on Arduino code.

[ted-hou]

We'll also need to figure out how to trim out unwanted event markers for older datasets.

[ted-hou]

Seems to be good.