src/config.c: Keep formatting and comments
src/config.c: Keep formatting and comments

Switch to using the new config_file_walk() helper in config_save() and
update existing configuration variables instead of blindly overwriting
the existing configuration file.

Note: This breaks configuration setting storage if one or more settings
are missing in the configuration file. We need to refactor our parser
and serialization routines another time before this can be implemented
properly, though.

Signed-off-by: Lukas Fleischer <af90e31281d8305af43dc616c5aaca3c7165f8a7@cryptocrack.de>

lfos/calcurse,lfos/calcurse,lfos/calcurse