Removed preference to disable halos

There's really no reason to have this anymore. It was (AFAIK) introduced years ago
as a performance-saving measure, then was moved to Advanced Preferences in 1.13 since
modern PCs mostly have no issues. With accelerated rendering, there's even less of a
reason to have this.

changelog.md

@@ -7,6 +7,7 @@
    * Removed incomplete joystick support.
    * Removed map scaling algorithm customization. Nearest-neighbor scaling will now
      always be used.
+   * Removed option to disable unit and item halos.
  ### Language and i18n
    * Updated translations: British English, Chinese (Simplified),
      Chinese (Traditional), Czech, French, Galician, German, Italian, Japanese,

data/advanced_preferences.cfg

@@ -159,14 +159,6 @@
     default=yes
 [/advanced_preference]
 
-[advanced_preference]
-    field=show_halos
-    name= _ "Show haloing effects"
-    description= _ "Show special unit graphical effects"
-    type=boolean
-    default=yes
-[/advanced_preference]
-
 [advanced_preference]
     field=show_deprecation
     name= _ "Show deprecation messages in-game"

src/halo.cpp

@@ -263,7 +263,7 @@ void halo_impl::remove(int handle)
 
 void halo_impl::render()
 {
-	if(!preferences::show_haloes() || halos.empty()) {
+	if(halos.empty()) {
 		return;
 	}
 

src/preferences/game.cpp

@@ -40,8 +40,6 @@ namespace {
 
 bool message_private_on = false;
 
-bool haloes = true;
-
 std::map<std::string, std::set<std::string>> completed_campaigns;
 std::set<std::string> encountered_units_set;
 std::set<t_translation::terrain_code> encountered_terrains_set;
@@ -82,7 +80,6 @@ manager::manager() :
 	set_music_volume(music_volume());
 	set_sound_volume(sound_volume());
 
-	set_show_haloes(preferences::get("show_haloes", true));
 	if (!preferences::get("remember_timer_settings", false)) {
 		preferences::erase("mp_countdown_init_time");
 		preferences::erase("mp_countdown_reservoir_time");
@@ -858,17 +855,6 @@ void set_message_private(bool value)
 	message_private_on = value;
 }
 
-bool show_haloes()
-{
-	return haloes;
-}
-
-void set_show_haloes(bool value)
-{
-	haloes = value;
-	preferences::set("show_haloes", value);
-}
-
 compression::format save_compression_format()
 {
 	const std::string& choice =

src/preferences/game.hpp

@@ -194,10 +194,6 @@ class acquaintance;
 	bool message_private();
 	void set_message_private(bool value);
 
-	bool show_haloes();
-	void set_show_haloes(bool value);
-
-
 	// Multiplayer functions
 	std::string get_chat_timestamp(const std::time_t& t);
 	bool chat_timestamping();