corrections in sha_tate
trac #16959: doctests for corrections in sha_tate
trac #16959: adjusting doctests
Trac #16959: p-primary bound for Sha can be improved

This ticket aims to improve the p-adic bit of sha_tate for elliptic
curves over Q.

* There are a few minor points to improve in the documentation (some of
the conditions are not stated precisely or slightly wrong).

* We can now allow reducible primes, too. Since #6406 we ask for the
p-adic rep to be surjective. However the recent results in [1] imply
that the bounds are also correct for all odd primes of semi-stable
reduction when the curve admits a p-isogeny.

* There is a small bug in padic_lseries, which made this fails:
{{{
sage: E = EllipticCurve("5040bi1")
sage: E.sha().p_primary_bound(5)
}}}
(reported by Charlene Soh).

[1] C Wuthrich, On the integrality of modular symbols and Kato's Euler
system for elliptic curves. Doc. Math. 19 (2014), 381–402.

URL: http://trac.sagemath.org/16959
Reported by: wuthrich
Ticket author(s): Chris Wuthrich
Reviewer(s): William Stein