Adding flow validation plots presenting io_group and io_channel infor…

[edhinkle]

…mation in flow hits datasets.

[edhinkle]

I've tested the addition of these new validation plots on a file with io_group and io_channel in the hits datasets and on MiniRun4 file, which doesn't have these fields. The plots are only created if the fields exist in the hits datasets, but the script runs whether or not the fields exist.