Discord RPC cleanup

- Loading Discord RPC is now handled by `load/rpc.lua`
- Removed `presence` global, call `DiscordRPC:update()` directly with what needs updating
- Game doesn't crash anymore if the Discord RPC fails to load
- Added RPC variables in the gamemode superclass to let each gamemode handle its special case

scene/game.lua

@@ -5,13 +5,10 @@ function GameScene:new(game_mode, ruleset)
 	self.game = game_mode()
 	self.ruleset = ruleset()
 	self.game:initialize(self.ruleset)
-	if game_mode.name == "Demon Mode" and math.random(1, 7) == 7 then
-		presence.details = "Suffering"
-	else
-		presence.details = "In game"
-	end
-	presence.state = game_mode.name
-	discordRPC.updatePresence(presence)
+	DiscordRPC:update({
+        details = self.game.rpc_details,
+        state = self.game.name,
+    })
 end
 
 function GameScene:update()