Attempted to fit different resolutions better.

- Height of #main is set based on document.documentElement.clientHeight on window.onload.
	* This is not a very good solution, e.g. there's a few pixels of whitespace at the bottom on larger resolutions and it only gets set onload, but it works better than before.
- Changed checkIfStarted() to checkTimerState().
- Changed getInputTime() to startTimer().