1. Improved the constructor. Now it has better performance when data is
vary large (e.g. >1M).
2. Fixed line 99. When bin==numBins, the value falls on the next bin of
the max bin, not right on the edge.

Update .gitignore

Combining Area & Line plots. Text alignment of axis labels. Supporting demo

Added text-alignment functionality for axis labels. Added functionality for combining both line & area plots on one chart. Added demo of functionality added.