Adds Gene Targetting mode to Floral Somatoray

While I was rooting around in hydroponics code, I saw that a list was being regenerated with UI interaction, so I threw the list into the plant controller.

No proper sprites for the Floral Somatoray's new mode yet, but it uses the gun sprite from mutate mode, and the projectile sprite from yield mode.

code/datums/repositories/decls.dm

@@ -0,0 +1,39 @@
+/var/repository/decls/decls_repository = new()
+
+/repository/decls
+	var/list/fetched_decls
+	var/list/fetched_decl_types
+	var/list/fetched_decl_subtypes
+
+/repository/decls/New()
+	..()
+	fetched_decls = list()
+	fetched_decl_types = list()
+	fetched_decl_subtypes = list()
+
+/repository/decls/proc/decls_of_type(var/decl_prototype)
+	. = fetched_decl_types[decl_prototype]
+	if(!.)
+		. = get_decls(typesof(decl_prototype))
+		fetched_decl_types[decl_prototype] = .
+
+/repository/decls/proc/decls_of_subtype(var/decl_prototype)
+	. = fetched_decl_subtypes[decl_prototype]
+	if(!.)
+		. = get_decls(subtypesof(decl_prototype))
+		fetched_decl_subtypes[decl_prototype] = .
+
+/repository/decls/proc/get_decl(var/decl_type)
+	. = fetched_decls[decl_type]
+	if(!.)
+		. = new decl_type()
+		fetched_decls[decl_type] = .
+
+/repository/decls/proc/get_decls(var/list/decl_types)
+	. = list()
+	for(var/decl_type in decl_types)
+		.[decl_type] =  get_decl(decl_type)
+
+/decls/Destroy()
+	crash_with("Prevented attempt to delete a decl instance: [log_info_line(src)]")
+	return 1 // Prevents Decl destruction

code/datums/repositories/repository.dm

@@ -1,4 +1,19 @@
+/repository/New()
+	return
+
 /datum/cache_entry
 	var/timestamp
 	var/data
 
+/datum/cache_entry/New()
+	timestamp = world.time
+
+/datum/cache_entry/proc/is_valid()
+	return FALSE
+
+/datum/cache_entry/valid_until/New(var/valid_duration)
+	..()
+	timestamp += valid_duration
+
+/datum/cache_entry/valid_until/is_valid()
+	return world.time < timestamp