Handle categorical data

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IFC Soft should be able to load data with categorical dimensions (both by 
string or by number). The SOM algorithm should treat being in a different 
category as being a distance of 1. The program should let you select groups of 
data points or data sets by the categories and make hit histograms based on 
them.

Original issue reported on code.google.com by kyle.tha...@gmail.com on 13 Apr 2011 at 8:16