Settings GUI: Add support for DECIMAL1 settings.

src/settings_internal.h

@@ -48,6 +48,7 @@ enum SettingGuiFlagLong {
 	SGF_NEWGAME_ONLY = 1 << 6, ///< this setting cannot be changed in a game
 	SGF_SCENEDIT_TOO = 1 << 7, ///< this setting can be changed in the scenario editor (only makes sense when SGF_NEWGAME_ONLY is set)
 	SGF_PER_COMPANY  = 1 << 8, ///< this setting can be different for each company (saved in company struct)
+	SGF_DECIMAL1     = 1 << 9, ///< display a decimal representation of the setting value divided by 10
 };
 DECLARE_ENUM_AS_BIT_SET(SettingGuiFlagLong)
 typedef SimpleTinyEnumT<SettingGuiFlagLong, uint16> SettingGuiFlag;