Don't filter shebangs when using the 'some' comment filter

Also clarify documentation a bit more about using regexp as filter

lib/output.js

@@ -101,6 +101,7 @@ function OutputStream(options) {
                 // multiline comment
                 return /@preserve|@license|@cc_on/i.test(text);
             }
+            return type == "comment5";
         }
     }
     else if (options.comments){ // NOTE includes "all" option