Diona and Synth bugfixes (#5546)

- Diona are no longer blind all the time. Fixes #5543
- Radium doesn't spam Diona with messages. Fixes #5544 
- Synthetics like AI/cyborgs/PAI can now talk. Fixes #5516

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

@@ -149,7 +149,7 @@
 		return null
 
 	var/obj/item/organ/O = internal_organs_by_name[species.vision_organ]
-	if (no_synthetic && O.status & ORGAN_ROBOT)
+	if (!istype(O, /obj/item/organ/eyes) || (no_synthetic && (O.status & ORGAN_ROBOT)))
 		return null
 
 	return O

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

@@ -164,7 +164,7 @@
 	//Vision
 	var/obj/item/organ/vision
 	if(species.vision_organ)
-		vision = internal_organs_by_name[species.vision_organ]
+		vision = organs_by_name[species.vision_organ]
 
 	if (!vision)
 		if (species.vision_organ) // if they should have eyes but don't, they can't see

code/modules/mob/living/silicon/say.dm

@@ -19,7 +19,7 @@
 			speech_problem_flag = 1
 			message = Gibberish(message,damaged-10)
 
-	var/list/returns[3]
+	var/list/returns[4]
 	returns[1] = message
 	returns[2] = verb
 	returns[3] = speech_problem_flag