With the changed des_old API, let's complete the work by renaming the

functions in ui_compat.  This gave reason to rework that part more
thoroughly, so here are the changes made:

1. Add DES_read_password() and DES_read_2passwords() with the same
   functionality as the corresponding old des_ functions, as a
   convenience to the users.
2. Add UI_UTIL_read_pw_string() and UI_UTIL_read_pw() with the
   functionality from des_read_pw_string() and des_read_pw(), again as
   a concenience to the users.
3. Rename des_read_password(), des_read_2passwords(),
   des_read_pw_string() and des_read_pw() by changing des_ to
   _ossl_old_des_, and add the usual mapping macros.
4. Move the implementation of des_read_password() and
   des_read_2passwords() to the des directory, since they are tightly
   tied to DES anyway.

This change was inspired by a patch from Assar Westerlund <assar@sics.se>:

There are some functions that didn't get the kick-away-old-des-and-
replace-des-with-DES action.  Here's a patch that adds DES_ and des_
(in des_old.h) versions of des_read_pw_string et al.  This patch
includes some of the first des_old.h semi-colon macro fixes that I've
already sent.