Pasta's digiprosthetics and gradient tweaks/additions (#5914)

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## About The Pull Request

Adds a tweaked variant of the synthliz fbp legs that works with most
clothing (Unbranded - Digitigrade) as well as adding/porting a few hair
gradients (Vertical Split (Back), Vertical Split (Back, Front Effect),
Shoulders (Flat), Wavy, Wavy Spiked, Striped, and Striped (Vertical).

## Why It's Good For The Game

Not enough digitigrade stuff aaaaaaaand a bit more gradient variety is
nice.

## Changelog

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:cl:
add: Unbranded - Digitigrade prosthetic legs
add:  7 hair gradients
/:cl:

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

@@ -4,8 +4,16 @@ GLOBAL_LIST_INIT(hair_gradients, list(
 	"Fade Low (Up)"		= "fadeup_low",
 	"Fade (Down)"		= "fadedown",
 	"Fade Low (Down)"	= "fadedown_low",
+	"Fade High (Down)"	= "fadedown_high",
 	"Reflected (Center)"= "reflected",
 	"Reflected Inverse (Center)"= "reflected_inverse",
+	"Vertical Split (Back)"= "vsplit_back",
 	"Vertical Split"	= "vsplit",
-	"Bottom (Flat)"		= "bottomflat"
+	"Vertical Split (Back, Front Effect)"= "vsplit_dual",
+	"Bottom (Flat)"		= "bottomflat",
+	"Shoulders (Flat)"	= "shouldersflat",
+	"Wavy"				= "wavy",
+	"Wavy Spiked"		= "wavy_spiked",
+	"Striped"			= "striped",
+	"Striped (Vertical)"= "striped_vertical"
 	))

code/modules/organs/external/robolimbs.dm

@@ -156,6 +156,12 @@ var/const/cyberbeast_monitor_styles= "blank=cyber_blank;\
 	icon = 'icons/mob/cyberlimbs/unbranded/unbranded_teshari.dmi'
 	unavailable_to_build = TRUE
 
+/datum/robolimb/unbranded_digitigrade
+	company = "Unbranded - Generic Digitigrade"
+	desc = "A digitigrade robotic leg of a fairly generic design."
+	icon = 'icons/mob/cyberlimbs/unbranded/unbranded_digitigrade.dmi'
+	parts = list(BP_L_LEG, BP_R_LEG, BP_L_FOOT, BP_R_FOOT)
+
 /datum/robolimb/nanotrasen
 	company = "NanoTrasen"
 	desc = "A simple but efficient robotic limb, created by NanoTrasen."