Move parser code and utility methods into separate modules to better
organize the code.  (The parser might well be called from within an
overall controller module that will read the phenotypes, call the parser
for the files we are interested in and then forward the results to a
yet-to-be defined analysis and reporting module.  So the code that
assumes file input and console output of results doesn't need to be
alongside the parser code.

Also, reorganize the results structure as {rsids:{(chromosome_number,
position):{group_label:{genotype:count}}}}, moving the label breakdown
inside the chromosome_number and position since it is likely at that
point that we would want to compare different groups.