* Refactoring (removed duplicate code for loading Challenge/OTP aux files)
* Added possibility to select aux file location manually if automatic "detection" (by constructing file paths) doesn't work. This is required so that aux files can be used with SAF which doesn't allow file path construction (maybe with OPEN_DOCUMENT_TREE, but that would involve additional user action and would require more permissions than required).
Manually selected aux file location is stored in preferences
* Fixed bug that OTP/Challenge mode wasn't correctly remembered
Philipp Crocoll