Put settings variables in a struct

Signed-off-by: Mattias Andrée <maandree@operamail.com>
Do all settings parsing, except from the command line, in settings.c

Signed-off-by: Mattias Andrée <maandree@operamail.com>
Separate out settings validation to settings.c, also print all errors before existing

Signed-off-by: Mattias Andrée <maandree@operamail.com>
Catch SIGUSR2 for reloading for settings

Signed-off-by: Mattias Andrée <maandree@operamail.com>
Implement reloading of configurations

Signed-off-by: Mattias Andrée <maandree@operamail.com>
Add reload menu item to redshift-gtk

Signed-off-by: Mattias Andrée <maandree@operamail.com>
Add optional transition when reloading settings

Signed-off-by: Mattias Andrée <maandree@operamail.com>
Print new settings, in verbose mode, when settings are reloaded

Signed-off-by: Mattias Andrée <maandree@operamail.com>
Merge branch reload into ma and resolve merge conflicts

Signed-off-by: Mattias Andrée <maandree@operamail.com>