feat: do not decrypt if the text file is newer than the encrypted file

This implies that the user may have changed the text file sometime
after they created the encrypted copy. So we do not decrypt the older
encrypted file---this would overwrite the text file.

calliope.sh

@@ -254,8 +254,13 @@ decrypt ()
                 then
                     echo "Decrypting $1 with $encryptionId"
                     nongpgfname="$(basename $1 .gpg)"
-                    $GPG_COMMAND --batch --yes --decrypt $1 > "$nongpgfname"
-
+                    if [ "$1" -nt "$nongpgfname" ]
+                    then
+                        $GPG_COMMAND --batch --yes --decrypt $1 > "$nongpgfname"
+                    else
+                        echo "WARNING: Decrypted file is newer than encrypted copy."
+                        echo "WARNING: Not overwriting. Please check the files, and re-encrypt if required."
+                    fi
                 else
                     echo "File is not a GPG encrypted file. Doing nothing."
                 fi