Bugfixes: Dronesay and Underwear/Socks in Character Setup (#2992)

This PR contains bugfixes for:

Drones being able to transmit empty messages when talking in local drone chat ("dronesay")
A possible runtime in dronesay, caused by a null-reference in player_list, or a mob not having a client
Underwear and Socks selection in Character Setup breaking when switching genders.
Character loadout is now sanitized each time before it gets displayed. Invalid selections will be reset to "None", when changing the character's gender.

code/modules/client/preference_setup/general/01_basic.dm

@@ -118,6 +118,9 @@
 
 	else if(href_list["gender"])
 		pref.gender = next_in_list(pref.gender, valid_player_genders)
+
+		var/datum/category_item/player_setup_item/general/equipment/equipment_item = category.items[4]
+		equipment_item.sanitize_character()	// sanitize equipment
 		return TOPIC_REFRESH
 
 	else if(href_list["age"])

code/modules/client/preference_setup/general/04_equipment.dm

@@ -35,12 +35,11 @@
 	var/undies = get_undies()
 	var/gender_socks = get_gender_socks()
 	if(!get_key_by_value(undies, pref.underwear))
-		pref.underwear = undies[undies[1]]
+		pref.underwear = null
 	if(!get_key_by_value(undershirt_t, pref.undershirt))
 		pref.undershirt = undershirt_t[undershirt_t[1]]
 	if(!get_key_by_value(gender_socks, pref.socks))
-		pref.socks = gender_socks[gender_socks[1]]
-
+		pref.socks = null
 
 /datum/category_item/player_setup_item/general/equipment/content()
 	. += "<b>Equipment:</b><br>"
@@ -49,7 +48,6 @@
 	. += "Socks: <a href='?src=\ref[src];change_socks=1'><b>[get_key_by_value(get_gender_socks(),pref.socks)]</b></a><br>"
 	. += "Backpack Type: <a href='?src=\ref[src];change_backpack=1'><b>[backbaglist[pref.backbag]]</b></a><br>"
 
-
 /datum/category_item/player_setup_item/general/equipment/proc/get_undies()
 	return pref.gender == MALE ? underwear_m : underwear_f