display a white dot on the black screen between questions to allow the user to focus on the area where the next question will be displayed
reduced available Colours for dry run
removed yellow Colour for real test run, as it's hard to read on the white background of the blood tube
proposed values for number of questions and time frames in the dry run
delay displaying the tube box and error detection notice after the blood tube
* Less invasive display of answer evaluation: instead of an alert()-dialog that could motivate a user to move their fingers away from the 'Y', 'N' and space-keys, e.g. to close the dialog with a mouse, the evaluation is displayed for a duration where the focus marker comes up next.
* Therefore, a cleaner time frame management became necessary: manageNextQuestion now has independant parts that display and hide their entire contents by themselves.
* Additionally, the answer evaluations have been promoted from strings to objects, in preparation of the upcoming real test run where their types need to be evaluated.
Refactoring: extracted KeyCodeHelper
Refactoring: removed delegating function
Refactoring: lock letter instead of key code as answer (better readable for  humans)
Refactoring: extracted JS Answer class