Add edges method
Fix node order in one test
Add checkNode method in test
Add checkEdge method and fix first test
Format tests with checkEdge method
Add an auto_increment primary key to all inputs
Take care of zero tolerance
Fix problem with zero tolerance
Check geom type and fix bug with null nodes
Fix almost all ST_Graph tests

TODO: Orient by slope
Add test for negative tolerances
Add primary key tests (0 and composite)