Update History Layout

[acrosman]

The graphs of previous days play are stacked vertically in history display. This isn't going to be sustainable as players use the program on a regular basis.

1. Add a graph of total play time at the top of the page.
2. Switch the graph layout to be a grid instead of vertically stacked.
3. Only show the most recent 6 days (three rows). Have a show more button the will display the rest.
4. Add more graph colors, make sure there are at least 10 distinct colors have been defined to allow for future expansion.