Fix event.key for keypress.

 It doesn't need to lookup keynames with keypress and shift

https://github.com/mootools/mootools-more/issues/1194

jsfiddle: http://jsfiddle.net/6xf4M/

With `keypress` shift+1 generates `keyCode` 33, which maps to `pageup` when this is added with `defineKeys`.