refactoring: more annotations
Enable in-band registration for opencaching.de

The strings still refer to the PIN code. That will be changed when
opencaching.pl, which shares the same interface, gets migrated as well
to the callback mechanism.
Update French translations from crowdin
refactoring: introduce PseudoList to handle non concrete lists

* should make adding a history list entry easier
* includes some non null annotations
* moved list code into separate package
Implements #3260, Images from opencaching.pl don't download

Loads them as spoilers like from gc.com
Merge branch 'issue-3260'
fix #3274: GPS Status app has a different icon
fix #3274: GPS Status app has a different icon
Enable in-band registration for opencaching.pl
Remove out-of-band registration for OAuth
refactoring: better names for methods
Use the right string for substitution
Merge branch 'release' into upstream
refactoring: remove unused string
Update strings
Reinstate err_auth_initialize string
Update translations
fix #3272: remove wrong extension from files
refactoring: add annotations and remove useless check
fix #3276: NPE because of a null log types