Changing a local passwd will now keep the encryption type that
was originally used to encrypt the password, so folks adding DES
to their systems will not be irritated/confused by having MD5'ed
passwords in their master.passwd. Coming later is an option to
allow the user to choose the encryption type.
2) Fix a bunch of compiler warnings announced by turning on -Wall.
I did not get them all, that will come a bit later.
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