adds snake coiling (#15514)

* new signals for resting and stop pulling

these are to be used as signals that will cancel the coiling

* Create coiling.dm

* Update coiling.dm

* adds sprite accessory for coiled naga

* main changes that apply the actual visuals to the coiling mechanics

* adds message to coiling, fixes offset, adds action icon

* coil offset was using old direction

* reordering

* fixes coil sprite not disappearing

* fixes offsets, solves loadout issue

* follows lin's suggestion and adds support for slimes by making it entirely handled in handle mutant

code/modules/client/preferences.dm

@@ -3066,6 +3066,7 @@ GLOBAL_LIST_EMPTY(preferences_datums)
 		save_character()
 
 	character.dna.features = features.Copy()
+
 	character.set_species(chosen_species, icon_update = FALSE, pref_load = TRUE)
 	character.dna.species.eye_type = eye_type
 	if(chosen_limb_id && (chosen_limb_id in character.dna.species.allowed_limb_ids))