Choose pipe number on initialize (#250)

* Choose pipe number on initialize

* Get pipe from base connection instance

* UE4 support

* Warnings as errors yelling

* Fix windows connection

* Oops all variables

* maybe this fixes it

* This one actually works!!!!

* Fix double function declaration

include/discord_rpc.h

@@ -64,7 +64,8 @@ typedef struct DiscordEventHandlers {
 DISCORD_EXPORT void Discord_Initialize(const char* applicationId,
                                        DiscordEventHandlers* handlers,
                                        int autoRegister,
-                                       const char* optionalSteamId);
+                                       const char* optionalSteamId,
+                                       int optionalPipeNumber);
 DISCORD_EXPORT void Discord_Shutdown(void);
 
 /* checks for incoming messages, dispatches callbacks */