Timer: fix input for foreign keyboards

Pro: works for non-qwerty keyboards
Con: a "backspace" effect:
![test](https://cloud.githubusercontent.com/assets/4411471/3958152/d675f77e-271c-11e4-839d-fe07307fc739.gif)
(this isn't really a big deal, just a caveat)
Looks like the `numericOnly` function isn't defined?