Now swim won't exit when a package is not installed, so that -qi or -ql works

without stopping.

SWIM/Ag.pm

@@ -68,7 +68,7 @@ sub description {
     }
       else { 
         print "package $argument is not installed\n"; 
-        exit;
+        return "not installed";
       }
   }
   untie %db;

SWIM/File.pm

@@ -532,7 +532,7 @@ sub file {
      if (defined $argument) {
         if (!defined $db{"$argument"}) {
          print "package $argument is not installed\n";          
-         exit;
+         return "not installed";
         }
      }
      nfile(\%commands);