Replace recursive algorithm with iterative algorithm
Merge remote-tracking branch 'upstream/master' into ticket-1861
Update inline documentation
Add an extra test of strongly connected components
Add an optimized WCC algorithm
Add another test for weakly connected components
Merge branch 'master' into ticket-1861
Address review comments: Use ITYPE instead of np.int32. Shorten long lines
Merge branch 'master' into ticket-1861
Merge pull request #460 from timleslie/ticket-1861

BUG: sparse.csgraph: make connected_components_directed work on large graphs