Added new error message incase number of valid samples isn't 512
Implement compact cache for the monitor waveform

New function fetch_csc_monitor_wavebins_v2 caches the meaned curve with
more than sufficient accuracy. This pulls from its own cache if it exists,
if not it pulls from the old cache generated by fetch_csc_monitor_wavebins
and manipulates it to get the meaned curve and cache it. If the old cache
does not exist the equivalent data is generated using
make_csc_monitor_wavebins, which still calls make_csc_periodic_bins_trials.
Note that get_long_monitor_curve is updated to refelect this change.