If logging initialization failed, the file logger would not be removed
correctly, and it would log to a GB_LOGFILES_DIR_IS_UNDEFINED directory.
Remove the file logger from the root appender, regardless of it being
null or not.
The issue can be easily reproduced before the fix by throwing an
exception in FileUtils#getExternalFilesDir. Before the fix, it would
still log to the aforementioned directory.
Aditionally, update the Settings screen to reflect that writing log
files is not available in such cases.
- moved out of GBApplication to class Logging
- the main thing is: when start()ing the FileAppender again, it *must*
- be configured to be non-lazy, otherwise it won't open the stream ever again.
