added generate_incompats() function
updated plot() methods for Population and TwoPops
removed diploid.py
introduced new Diploid class
updated symbolic module
added __init__.py file to create the fontana package
introduced a diploid module
introduced a diploid module
added hamming_dist() method to diploid
updated Network to be able to handle Diploid genotypes
split the old genotype module into network, population, evolution and metapopulation modules
minor edits