Animation for text horizontal scrolling

[SebastianJay]

In the HistoryWindow, we want the text to animate in a "one character every couple frames" type of fashion, similar to how many games have text horizontally scroll as narration or dialogue unfolds.

Within HistoryWindow, keep track of an index that shows how many characters can be displayed at once on screen within draw(), and increment that index within update() using timestep (once the time past exceeds a threshold, inc the index). The overall effect should be that as time passes, more characters will be displayed on screen.

Also, allow for a set of characters that have a different time threshold, such that they take longer to animate. This is mainly useful for the period . at the end of sentences -- a longer time conveys an actual pause as the words are "spoken.".The pause should occur after the "pause character" (period) appears; therefore, the higher threshold might technically apply to the character after the pause character.