Use a few more conditional tag elements

data/schema/core/addons.cfg

@@ -107,9 +107,13 @@
 	{SIMPLE_KEY leader string}
 	{SIMPLE_KEY random_leader string}
 	{DEFAULT_KEY random_faction bool no}
-	# TODO: below two keys only valid if above key is yes
-	{SIMPLE_KEY choices string_list}
-	{SIMPLE_KEY except string_list}
+	[if]
+		random_faction=no
+		[then]
+			{SIMPLE_KEY choices string_list}
+			{SIMPLE_KEY except string_list}
+		[/then]
+	[/if]
 	{SIMPLE_KEY terrain_liked terrain_list}
 [/tag]
 
@@ -195,10 +199,17 @@
 	[/tag]
 	# Multiplayer specific
 	# TODO: These are probably only allowed if type is mp or hybrid?
-	{DEFAULT_KEY min_players int 2}
-	{SIMPLE_KEY max_players int}
-	{DEFAULT_KEY allow_era_choice bool yes}
-	{DEFAULT_KEY require_campaign bool yes}
+	[if]
+		[not]
+			type=sp
+		[/not]
+		[then]
+			{DEFAULT_KEY min_players int 2}
+			{SIMPLE_KEY max_players int}
+			{DEFAULT_KEY allow_era_choice bool yes}
+			{DEFAULT_KEY require_campaign bool yes}
+		[/then]
+	[/if]
 [/tag]
 [tag]
 	name="era"
@@ -298,9 +309,15 @@
 	{SIMPLE_KEY victory_music string}
 	{SIMPLE_KEY theme string_list}
 	{DEFAULT_KEY victory_when_enemies_defeated bool yes}
-	# TODO: The following two keys are only valid if the above key is yes (or omitted)
-	{SIMPLE_KEY carryover_percentage int}
-	{SIMPLE_KEY carryover_add bool}
+	[if]
+		[not]
+			victory_when_enemies_defeated=no
+		[/not]
+		[then]
+			{SIMPLE_KEY carryover_percentage int}
+			{SIMPLE_KEY carryover_add bool}
+		[/then]
+	[/if]
 	{DEFAULT_KEY remove_from_carryover_on_defeat bool yes}
 	{DEFAULT_KEY disallow_recall bool no}
 	{DEFAULT_KEY experience_modifier int_percent 100}