REF: Compute flatcount lazy (so we do not need to know statistic in __init__)
REF: Compute flatcount lazy (so we do not need to know statistic in __init__)

tacaswell/scikit-xray,tacaswell/scikit-xray,tacaswell/scikit-beam,tacaswell/scikit-beam,Nikea/scikit-xray,Nikea/scikit-xray,scikit-xray/scikit-xray,danielballan/scikit-xray,danielballan/scikit-xray,tacaswell/scikit-beam,scikit-xray/scikit-xray,Nikea/scikit-xray,tacaswell/scikit-xray,danielballan/scikit-xray,scikit-xray/scikit-xray