develop for newest android version possible, support back to android 5
e.g.: Test, if API has a certain function. hide corresponding butten if not
TODO:
- change target and compile sdk to newest possible and see what errors there are (deprecated stuff)
- implement newer features
- also set minSDK to 21. some things to consider here are:
- dangerous (=runtime) permissions, ask user at installation not at runtime (if <23)