Added test for merge of fractions of edge ends
Added (failing) test for updating delta q based on joins, added initial (nonfunctioning) code for updating delta q's. Need some refactoring first...
Refactored delta modularity matrix: replaced TreeSet of delta modularities by TreeMap because of need for (fast) lookup
Removed redundant test
Improved names of instance variables in delta modularity matrix
Added functionality to remove delta modularities from max heaps for first joined community