Change preserve option to command line switch

Changes each adjustment method to take a preserve parameter when
setting the temperature instead of parsing the preserve option
from the command line/configuration file. This helps resolve the
issues around #513:

- This allows the preserve option to be implemented as a
  command-line switch (-P). This switch _disables_ the preservation
  of existing gamma ramps. Having a command-line switch makes it
  easier to use directly with manual or one-shot mode.
- The preserve options is on by default, so continual mode as well
  as other modes will default to applying the color adjustment
  on top of the current gamma ramps.
- Preserve is always disabled in reset mode so resetting works
  as expected again.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/redshift.h b/src/redshift.h
index f597c67..0282d83 100644
--- a/src/redshift.h
+++ b/src/redshift.h
@@ -88,8 +88,8 @@ typedef void gamma_method_print_help_func(FILE *f);
 typedef int gamma_method_set_option_func(gamma_state_t *state, const char *key,
 					 const char *value);
 typedef void gamma_method_restore_func(gamma_state_t *state);
-typedef int gamma_method_set_temperature_func(gamma_state_t *state,
-					      const color_setting_t *setting);
+typedef int gamma_method_set_temperature_func(
+	gamma_state_t *state, const color_setting_t *setting, int preserve);
 
 typedef struct {
 	char *name;