releases/v1.7.0

Lots of new cool stuff:

• Optimized for iOS 13 including dark mode
• Added auto-recovery of last session
• Added multi language support translated into: German, Chinese and Spanish
• Added cache size information
• Complete rebuild of the cache system
• Added imperial units support (feet, miles)
• Added tracking modes (Navigation, Fitness...)
• Added map source OpenTopoMap
• Small user interface improvements
• Many more small fixes and improvements

Special thanks to our team member @vincentneo who worked in many of the features. Also, thanks to Kurt Höblinger (@nitricware) who provided multilingual support and the German translation.