v1.3.0: Additional test statistics and accumulated updates

• Add arbitrary test statistics to new find_sets.py script, including predefined exclusivity, any co-occurrence, and all co-occurrence statistics -- see the WExT wiki for details.
• Add more accessible random seed to compute_mutation_probabilities.py script for mutation matrix permutations.
• Add optional FDR threshold to new find_sets.py script to limit output to statistically significant sets.
• Add additional examples, including those for new test statistics.
• Update documentation.