Fix broken ContentEditor references to missing lexical $table

Shockingly, this has been broken since this commit:

commit 13dcf431683126dc0ab2fef865a9c5061081cb88
Author: Mike Heins <mike@perusion.com>
Date:   Fri Sep 13 20:46:21 2002 +0000

But Perl didn't notice it until version 5.18.0, where it throws many
errors like this at Interchange startup time:

Calling UI...UserTag 'content_modify' subroutine failed compilation:

        Global symbol "$table" requires explicit package name at [...]