Feature: Display a graph of the training progress

[Timmeey86]

The idea is to save statistics for every training pack and day separately, e.g. in <bakkesmoddir>\data\customtrainingstatistics\<training pack ID/code>\<date_time>.log and then read all files of the same pack on demand in order to display the percentages. This feature is probably a lot of work since it requires:

• Figuring out how to reliably store data
• Figuring out when to store data (saving after every shot reset would allow restoring data in case of crashes, but that might write too often?)
• Figuring out how to draw a chart
• Implementing the chart, preferrably with one line per currently visible stat
• Implementing a legend for the chart so one can see which line means what
• Maybe get in touch with "Nobody" on the discord if they can recommend something for drawing charts which doesn't make the code review difficult

[Timmeey86]

Closed due to bad effort/improvement ratio. What we can do instead is implement a CSV export so users can copy that to stuff like MS Excel and draw a graph there if they want to.