Add expect filetype

bin/mkexec

@@ -45,7 +45,8 @@ my $bangs = {
     py   => `which python`,
     bash => '/bin/bash',
     sed  => `which sed`,
-    bc   => `which bc`
+    bc   => `which bc`,
+    exp  => `which expect` . " -f"
 };
 
 my $templates = {