Add Rich Presence parsing support

Adds support for parsing Rich Presences.

This can not be used for setting activities with bots.

Upgrade path:

Basically change your import and usage from
`serenity::model::gateway::Game` to
`serenity::model::gateway::Activity`.

3 files changed, 33 insertions, 6 deletions

diff --git a/tests/resources/game_1.json b/tests/resources/activity_1.json
index 4e8a4b4..4e8a4b4 100644
--- a/tests/resources/game_1.json
+++ b/tests/resources/activity_1.json
diff --git a/tests/resources/activity_2.json b/tests/resources/activity_2.json
new file mode 100644
index 0000000..12b0d4f
--- /dev/null
+++ b/tests/resources/activity_2.json
@@ -0,0 +1,26 @@
+{
+  "user": {
+    "id": "210141176211177474"
+  },
+  "status": "idle",
+  "game": {
+    "type": 2,
+    "timestamps": {
+      "start": 1524840854122,
+      "end": 1524841056674
+    },
+    "sync_id": "3MzqPLieWzTj5NW6WEzICu",
+    "state": "I Fight Dragons",
+    "session_id": "f737b052de95d8199723b92c1457463e",
+    "party": {
+      "id": "spotify:210141176211177474"
+    },
+    "name": "Spotify",
+    "flags": 48,
+    "details": "Pretend",
+    "assets": {
+      "large_text": "The Near Future",
+      "large_image": "spotify:a253f70af71e454b1021f8323357f6f983d622ed"
+    }
+  }
+}
diff --git a/tests/test_deser.rs b/tests/test_deser.rs
index 72c955d..dde1ff6 100644
--- a/tests/test_deser.rs
+++ b/tests/test_deser.rs
@@ -16,6 +16,13 @@ macro_rules! p {
     }};
 }
 
+// An activity with null type.
+#[test]
+fn activity() {
+    p!(Activity, "activity_1");
+    p!(Activity, "activity_2");
+}
+
 #[test]
 fn channel_create() {
     p!(ChannelCreateEvent, "channel_create_1");
@@ -41,12 +48,6 @@ fn emoji_animated() {
     p!(Emoji, "emoji_animated");
 }
 
-// A game with null type.
-#[test]
-fn game() {
-    p!(Game, "game_1");
-}
-
 #[test]
 fn guild_ban_add() {
     p!(GuildBanAddEvent, "guild_ban_add_1");