Make Displayed Graph Adhere To Underlying Dataset

This modifies the algorithm used to determine the graph's line. The old
algorithm, although generating prettier graphs, displayed inaccurate
information; line arcs would go above and below min/max values & a
graph that had two data points of the same value in a row would show
invalid arcs between the two data points (always upward) giving the
user an inaccurate representation of the data.