[MacPerl] Update on Medline script

[Gene Hsu <genehsu@umich.edu>]

I just tried my script on three other systems (SunOS 4.1.3, Solaris 2.4, 
HP-UX 9.07) and things work as advertized on those systems.  So I'm 
ruling out a bug in my script.

The bug occurs in the following instances for me: (MacPerl 5.0.6r1m)

(1)
my %refs = %reference;
$refs{AU} = whatever;

(2)
my %refs;
%refs = %reference;
$refs{AU} = whatever;

I haven't tried too much else.

-- Gene