Coloring more than two taxonomies (input/alignment visualization)

[nfranz]

See also Issue #6
The attached input file, run with either:

1. euler -i Synth1.txt -e mnpw --rcgo
2. euler2 align Synth1.txt and then: euler2 show iv and euler2 show pw
   ..the input and alignment visualizations do not consistently show three colors corresponding to the three taxonomies' concept regions.
   Synth1.txt