Fix order of sorting for cyclic dependencies

[esserj]

Fix order of sorting for cyclic dependencies where multiple dependencies are assumed to always go after the cyclic one

In the test case: Lets assume none of the FK allow cascading deletes

Removing Node 1 would be blocked by Node 2 Removing Node 2 would be blocked by Node 3 and Node 5 Removing Node 3 would be blocked by Node 4 -> cyclic through 4 -> 2 -> 3 Removing Node 4 would be blocked by Node 2 -> cyclic through 2 -> 3 -> 4 Removing node 5 is not blocked by any nodes

So We need to first remove Node 5, which is not blocked by any node And Node 1 is not part is a cyclic dependency itself, but Node 2 references it, so Node 1 must always come somewhere after Node 2, which is part of a cyclic dep so Node 1 should then come after the other nodes

The rest of the nodes [2, 3, 4] are locked in cyclic dep. so we cannot really resolve them in a favourable way, unless we try to identify which dependencies are blocking and which ones are not (deleting/nulling FKs or not), only listing the blocking dependencies should also resolve the issue, making the chance of success higher, this is however done by the Purger

[esserj]

This will fix https://github.com/doctrine/data-fixtures/issues/329

[esserj]

It might also fix https://github.com/doctrine/data-fixtures/pull/127 Because truncate would no longer be done on a table that is still referenced elsewhere