Add softswitch reads for display modes

Fixes #32

The RdAltChar (mousetext) is not accurate. Under Virtual II it seems
to always return true if the 80 column firmware is active, regardless
of which character set is active.

script.js

@@ -69,6 +69,9 @@
           hires2.show(false);
           tty.splitScreen(0);
         }
+      },
+      getState: function() {
+        return Object.assign({}, this.state);
       }
     };
     var pdl = [0, 0, 0, 0];