Supporter Retention, API Rewrite, and Escapes Pie Fix

Update time once again, as there are several people nearing a month's worth of matches I've now added the 180 days of retention for supporters. Along with it comes a date range filter on the overview page, and the ability to upload matches from any time in that period.

Now that I better understand NightLight’s needs I’ve pushed a major reorganisation/rewrite of the statistics API which simplifies certain aspects and will help in adding future features.

The last small thing is I’ve fixed the escapes pie chart showing the incorrect number of 0 kill games under certain situations.