(mu-citation-name-alist): Deleted.

(mu-citation-name-alist): Deleted.
(mu-cite-load-registration-file): Initialize value of
`mu-registration-symbol' if it is not bound.
(mu-cite-save-registration-file): Use `(symbol-value
mu-registration-symbol)' instead of `mu-citation-name-alist'.
(mu-register-get-citation-name): Likewise.
(mu-register-add-citation-name): Use `(set-alist
mu-registration-symbol ...)'.