fix(log): bypass ValueError

[bencrts]

Fixes #128

The sage.all.log() function does not throw the same error found in math.log(), so can be used as a bypass. However, it's much slower (~50x in some cases) so I did not just directly swap it out.

It's a bit unsatisfactory, though, but it works.

[bencrts]

After the fix:

sage: est = LWE.primal_bdd(param, red_cost_model = classic_model)
sage: est
rop: ≈2^135.2, red: ≈2^127.9, svp: ≈2^135.2, β: 317, η: 408, d: 261595, tag: bdd

[bencrts]

If there's any suggestion on a better way to handle it, let me know

[malb]

Is the consensus we should merge this or is there another way?

[bencrts]

I'll have a look at @ludopulles suggestion on #128 to see if I can implement his suggested fix first.