adds: gm tool for creating prop pdas convo for events

* Creates new proc in pda/messenger.dm to handle fake conversation creation
* Creates new eventkit datum and holder var on client for remembering identitities
* Creates new proc as eventkit R_FUN verb for managing prop identities
* Creates new proc on pda to create a fake event prop conversation in new eventkit
* Creates new topic in admin/view_variables/topic.dm and helper.dm to call new proc on pda

code/modules/client/client defines.dm

@@ -47,6 +47,7 @@
 	var/last_message_count = 0
 	var/ircreplyamount = 0
 	var/entity_narrate_holder //Holds /datum/entity_narrate when using the relevant admin verbs.
+	var/fakeConversations //Holds fake PDA conversations for event set-up
 
 		/////////
 		//OTHER//