Bugfix in padic_log.
Bugfix in padic_log.

The bound on the number of terms used in the logarithm computation
was sometimes to low.  Now I have chosen a bound that I have proven,
see e.g. in my thesis.

jpflori/flint2,fredrik-johansson/flint2,dsroche/flint2,jpflori/flint2,wbhart/flint2,dsroche/flint2,dsroche/flint2,dsroche/flint2,jpflori/flint2,jpflori/flint2,wbhart/flint2,fredrik-johansson/flint2,fredrik-johansson/flint2,wbhart/flint2