Fixup event names

- GAME_XXXXX not XXXXX_GAME
- Nuked the WantsPresence event

include/discord-rpc.h

@@ -27,7 +27,6 @@ typedef struct DiscordEventHandlers {
     void (*ready)();
     void (*disconnected)(int errorCode, const char* message);
     void (*errored)(int errorCode, const char* message);
-    void (*presenceRequested)();
     void (*joinGame)(const char* joinSecret);
     void (*spectateGame)(const char* spectateSecret);
 } DiscordEventHandlers;