Display analytic rank for ECNF in more cases.

[roed314]

When I look at 2.0.10691.1-1.0.1-a1 the analytic rank is shown as "not available" but the L-function shows the analytic rank as 1. It would be nice to either port analytic ranks over to db.ec_nfcurves from L-functions or to update the ecnf pages on the fly when the information is available in the L-function.

[roed314]

See this comment for some context.