[with patch, is fixed] graphs: enum() functionality duplicated in relabel()

[jason]

The enum() code is duplicated in relabel() for the quick option. It sure would be nice to factor that out so that the enum() code was all in one place.

[rlm]

See ticket #729 for some relevant comments...

[rlm]

Or instead, just read them here:

cmp ultimateley ends up using enum() twice, and this is kind of too much, since we could just look at the two graphs from lexicographically most significant, and return the answer as soon as they differ. Also, as Jason points out we should be using eq, neq, lt, le, gt, ge instead.

[rlm]

Note - the quick option in the relabel function was originally an optimization for the graph_isom code, and no longer applies, since it is never used. Other than that purpose, it doesn't make sense to have it as an option, so I'll just remove it.

Here is another aspect:

sage: G._nxg.adj
{0: {1: [None]}, 1: {0: [None]}}
sage: H._nxg.adj
{0: {1: [None, None]}, 1: {0: [None, None]}}
sage: G == H
True

[rlm]

There is an attached patch that cleans up the whole situation.

[rlm]

This one first, removed quick option from relabel().

[rlm]

This is the main overhaul.