- The stabledag module uses the root WouldCycle.

- Removed commented methods not implemented by petgraph.
- Re-formated the stabledag.rs file to have the same format as lib.rs:
	- In the where clauses, it uses the same space formatting as in lib.rs.
	- Re-formated some comments to fit in 100 columns.
- Corrected typo in the description of the module.

Author: davenza