added:
- ABOUT: complete changelog (english only)

fixed:
- main menue: if less then 8 player names are registered, its impossible to reduce player count without adding more player names (thanks to Markus)
- when score input is set to "Set of THREE Darts": impossible scores are accepted, like 179 (thanks to Fabian)
- no checkout suggesstion above 170 (needed for master out)
- wrong inital checkout suggestion in FREE mode with score below 180
- minor code refactoring
