push

Push every sample in chunk (EEG columns first, then accel x/y/z, then gyro x/y/z, then the contact companions) as one LSL chunk. No-op for an empty chunk. The chunk's column count must match this outlet's. EegChunk.contact is one flag per channel for the whole chunk, so the same 1.0 / 0.0 row is repeated on every sample of the chunk.