Added timeout value for better speed training.

You can change the timeout between 2 characters from
3 to 30 dots. If you need longer than the adjusted
timeout to type in the character, it will be marked as
wrong. This training is better for speed, because you
must answer immediatly.

The length of a dot is calculated with this formula:

T = 1200 / wpm
(T = duration of dot, wpm = Words per Minute)

Example:

The pause between two characters is defined as 3 dots.
At a speed of 20wpm one dot has a length of 60ms. So
you must recognized and typed in the character within
180ms.