Bug: Scrolling in Typing test text block

[NathanDavis-UW]

You are currently able to score down manually in the typing test text block. This feature serves no purpose and can lead to the user accidentally scrolling down and being forced to scroll back up to see the top of the test.

[laelath]

This was a problem that I encountered when I first started the program, not sure how to not allow manual scrolling, but allow automatic scrolling in GTK.