added code to do so-called fake strfs
interesting little bug where the calc_psth_by_stim would have weird edge effects because of an unexpected interaction with rast2spktimes. rast2spktimes returns integers (as floats), which get binned weirdly when you give integer millisecond bins in calc_psth_by_stim. adding 0.1 ms to each of the spiketimes resolves the issue so that calc_psth_by_stim gives results that are consistent with simply summing down the raster columns.