Incorporation and small clean-up of Fredrik's padic_exp code
Incorporation and small clean-up of Fredrik's padic_exp code

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