Factor out the nonresidue code for qadic/sqrt.
On the way to qadic_sqrt for p=2.

This particularly commit most certainly won't compile, but
I want to save my state right now to include the 2.4 release.
Merge branch 'padic' of https://github.com/wbhart/flint2 into padic
Adds _fmpz_vec_scalar_fdiv_r_2exp.

No test code so far.  But then again, this functions just calls
fmpz_fdiv_r_2exp for each coefficient.
Bugfix in fmpz_vec_scalar_fdiv_r_2exp().

I had messed up the function name in the previous commit.
Another intermediate commit for qadic_sqrt_2().
Adds "fmpz_mat_charpoly()."
Bugfix for fmpz_mat_transpose.
Stash qadic_sqrt changes, not working yet.
Adds fmpz_poly_mat_transpose().
Fix includes for fmpz_poly_mat_transpose.
Adds padic_mat_get, set_fmpq_mat(), and _nrows(), _ncols().
Small update to "qadic".

Small allocation fix to qadic_frobenius,
and added 1 byte to the allocation of ctx->var.
Improve qadic_inv in the case len = 1.
Improve examples/qadic
Adds qadic_set_fmpz_poly.
Bugfix for FLINT_ABS.
Adds qadic_gen and qadic_set_ui.
Adds an example file for radix conversion over Z/nZ.

I'll also use this as an example in my DPhil thesis
where radix conversion features as the single most
time consuming step.
Merge branch 'padic' of https://github.com/wbhart/flint2 into padic