Update Cope.pm

avoid:

given is experimental at /usr/local/share/perl/5.18.2/App/Cope.pm line 255.
when is experimental at /usr/local/share/perl/5.18.2/App/Cope.pm line 256.
when is experimental at /usr/local/share/perl/5.18.2/App/Cope.pm line 259.
when is experimental at /usr/local/share/perl/5.18.2/App/Cope.pm line 262.
 on newer version of perl