title: Syntax highlighting not looking at shebang line on known filetypes
body: <p>I have a Perl file with an atypical naming convention (e.g. file = test.cfg) and *.cfg is a known file extension for an existing filetype in my vim install.  Is there a vimrc setting that will tell vim to use the shebang value, regardless of the file extension?  I know I can put <code># vim: set filetype=perl :</code> in the file itself as an alternate solution.  I want vim to look @ the shebang value first, then the file extension.</p>
  
  <pre><code>#!/usr/bin/perl
  my $var = "please highlight me";
  </code></pre>