Adds HIDEHORNS bitflag (wigzards can live) (#2715)

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## About The Pull Request
Adds new HIDEHORNS bitflag for things that need to hide horns and shifts
mask+head handling to use it instead of HIDEHAIR.
This means wigs now 
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## Changelog

:cl:
fix: Wigs no longer hide Sarathi horns
/:cl:

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code/__DEFINES/inventory.dm

@@ -52,13 +52,14 @@
 #define HIDESUITSTORAGE (1<<1)
 #define HIDEJUMPSUIT (1<<2)	//these first four are only used in exterior suits
 #define HIDESHOES (1<<3)
-#define HIDEMASK (1<<4)	//these last six are only used in masks and headgear.
-#define HIDEEARS (1<<5)	// (ears means headsets and such)
-#define HIDEEYES (1<<6)	// Whether eyes and glasses are hidden
-#define HIDEFACE (1<<7)	// Whether we appear as unknown.
+#define HIDEMASK (1<<4)		//these last six are only used in masks and headgear.
+#define HIDEEARS (1<<5)		// (ears means headsets and such)
+#define HIDEEYES (1<<6)		// Whether eyes and glasses are hidden
+#define HIDEFACE (1<<7)		// Whether we appear as unknown.
 #define HIDEHAIR (1<<8)
 #define HIDEFACIALHAIR (1<<9)
 #define HIDENECK (1<<10)
+#define HIDEHORNS (1<<11) 	// Used for hiding Sarathi horns.
 
 //bitflags for clothing coverage - also used for limbs
 #define HEAD (1<<0)

code/modules/mob/living/carbon/human/species.dm

@@ -809,7 +809,7 @@ GLOBAL_LIST_EMPTY(roundstart_races)
 			bodyparts_to_add -= "face_markings"
 
 	if("horns" in mutant_bodyparts)
-		if(!H.dna.features["horns"] || H.dna.features["horns"] == "None" || H.head && (H.head.flags_inv & HIDEHAIR) || (H.wear_mask && (H.wear_mask.flags_inv & HIDEHAIR)) || !HD)
+		if(!H.dna.features["horns"] || H.dna.features["horns"] == "None" || H.head && (H.head.flags_inv & HIDEHORNS) || (H.wear_mask && (H.wear_mask.flags_inv & HIDEHORNS)) || !HD)
 			bodyparts_to_add -= "horns"
 
 	if("frills" in mutant_bodyparts)