Add documentation to cost_size and cleanup style.
Start writing documentation for cost2thresh.
Cleanup and add documentation to threshold_arr and thresholded_arr.
Fix error I introduced to cost_size docstring.
Clean up and add documentation to cost2thresh.
Replace cost_size with new function make_cost_array.
Update old print statements to use print function.
Write apply_cost and its test.
Clean up and add documentation to nodal_pathlengths.
Start to clean up nodal_summaryOut.
Correct distance calculation for disconnected nodes.
Merge tests for nodal metrics into a TestCase.
Write inter_node_distances w/ test, update nodal metric functions.
Rename G graph, iterate through sorted dicts of node metrics.
Resurrect cost_size (w/ DeprecationWarning), write test for it.
Merge pull request #5 from dabliss/dan-dev

Clean up some functions in util and metrics
corrected ArithmeticError typo, added another ArithmeticError instance
NF: added check_integrity method to GraphPartition, check no empty partitions
NF: added check for NaNs to check_integrity GraphPartition method
RF: update check_integrity docstring