added orr() method
added generate_from_random_incompats() method
fixed link to RMSD() method
made generate_from_random_incompats() method generate connected nets
created incompats attribute
disallowed ancestral-ancestral incompatibilities
fixed bug in stable() method to and extended it \
to deal with circles
minor edits
minor edits
minor edits
changed TwoPops.get_genetic_variation() methods \
to calculate parameters per site; added reproductive isolation method
minor edits
made infinite N default and added get_differentiation() \
method