Only show the battery optimization settings if the intent can be handled (on samsung devices with Android 6 for example it throws ActivityNotFoundException)

Currently translated at 96.4% (27 of 28 strings)

Translation: Nebulo/General strings
Translate-URL: https://weblate.frostnerd.com/projects/nebulo/nebulo/nl/

Currently translated at 96.4% (27 of 28 strings)

Translation: Nebulo/General strings
Translate-URL: https://weblate.frostnerd.com/projects/nebulo/nebulo/nl/

Fixed #80

Implements #57

Implements #48

Exporting the queries takes time, in which the user might have left the settings. Thus the export has to check whether the fragment is still attached

Added settings to allow/deny IPv4/IPv6 traffic, even if IPv4/IPv6 isn't enabled for the app (can be used to enforce IPv4/IPv6 only modes)

Implements #36

Implements #30

Changed the .dohserver file format (now contains the HttpsDnsServerInformation, not only name & server URLs), changed how server configurations are being saved

Implements #25

Added a setting which null-terminates domains blocked by keweon (only visible when keweon is active as primary server)

Fixes #21

Implements #16

Implements #14