Implement Discord Rich Presence (#1137)

* add discord rpc library

* add discord rpc

* add cutscene check

* fix build (hopefully)

* fix build

* edit paths

* Replace prebuilt discord-rpc lib with repo clone

game/main.cpp

@@ -8,6 +8,10 @@
 #include "common/versions.h"
 #include "common/log/log.h"
 #include "common/util/FileUtil.h"
+#include "game/discord.h"
+
+// Discord RPC
+extern int64_t gStartTime;
 
 void setup_logging(bool verbose) {
   lg::set_file(file_util::get_file_path({"log/game.txt"}));
@@ -32,6 +36,9 @@ int main(int argc, char** argv) {
     }
   }
 
+  gStartTime = time(0);
+  init_discord_rpc();
+
   setup_logging(verbose);
 
   while (true) {