More functionality in segproj

[hemingur]

I would like to see additional functionality in segproj beyond -sumcol.
I would be useful to be able to use float columns and also compute quantities such as mean, median, min, max etc.
I would suggest a new switch -summarycol [A,B,C,...] and -summaryfunc [F1,F2,F3,...] (or -sc and -sf)
where A, B etc. are numerical columns from the file/stream and F1, F2 etc. are the summary functions to apply to those columns.