Add reduce_kwargs to Study and BaseData.plot_dimensionality_reduction to allow for passing arguments without breaking functionality
Move bins option of reduce to BaseData
Add xticklabels to violin
Move `plot_pooled_dot` from visualize.splicing --> visualize.generic
threshhold Expresssion.data so there's NaNs for data lower than the threshold
Set `binify` to default to False for splicing reduction
add checks for whether all the groups are present in the data, and leave an empty spot if not