Added optional data for Q(sqrt(-1))

Added optional data (rank, generators, analytic rank and conjectural
#Sha) for curves over Q(sqrt(-1)). There are two exceptions, namely
[4338,531,3].a3 and [4338,915,3].b3 both with very large a-invariants,
where we were able to determine the rank (r=1), but could not find a
generator.