v7.0 Lots of fixes & features

• Implement a feature where you can save the statistics to a file
• Fix key capacity checks being incorrect
• Implement 6 additional rendering modes
  
• Improve overall performance
• Fix changing the update rate messing up the average
• Fix a multithreading issues (as kindly pointed out by freakode)
• Lots of internal refactoring & optimizations
• Improve startup times
• Fix a bug with the rendering mode loading (bea5316) (#12)