Fixed bug where graph with 1 user/1 artist would throw an exception
Added cachine of data on graph page (for 2 days)
note: doesn't take into account different ordering of parameters
Fixed graph data caching, should be resistant to parameter order changing
Fixed (serious!) caching problem, added color palettes (still pretty rough)
Added option to delete a color scheme
Color options - changing the palette does so without reloading the page.
Added some default color schemes for colorblind persons