A channel with more than max_bins (default 100000) events in the requested
range comes binned on the server (round bin width, average plus min/max/count
columns) instead of raw, the way databoard does it: 24 h of one 100 Hz BS
channel was 23 s and 3 GB raw, now about 5 s. Channels with fewer events stay
raw. A warning names the binned channels; bins= chooses the binning
explicitly, max_bins=None always fetches raw events.