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/title.lua

@@ -7,13 +7,27 @@ local main_menu_screens = {
     ExitScene,
 }
 
-local mainmenuidle = {"Idle", "Twiddling their thumbs", "Admiring the main menu's BG", "Waiting for spring to come"}
+local mainmenuidle = {
+    "Idle",
+    "On title screen",
+    "On main menu screen",
+    "Twiddling their thumbs",
+    "Admiring the main menu's BG",
+    "Waiting for spring to come",
+    "Actually not playing",
+    "Contemplating collecting stars",
+    "Preparing to put the block!!",
+    "Having a nap",
+    "In menus",
+    "Bottom text",
+}
 
 function TitleScene:new()
 	self.main_menu_state = 1
-	presence.details = "In menus"
-	presence.state =  mainmenuidle[math.random(#mainmenuidle)]
-	discordRPC.updatePresence(presence)
+	DiscordRPC:update({
+        details = "In menus",
+        state =  mainmenuidle[math.random(#mainmenuidle)],
+    })
 end
 
 function TitleScene:update()