Implement preferred emote quality setting.

This doesn't work super well for Twitch emotes because they don't
conform to a proper emote scaling standard

Fixes #150

src/util/emotemap.hpp

@@ -3,6 +3,8 @@
 #include "messages/lazyloadedimage.hpp"
 #include "util/concurrentmap.hpp"
 
+#include <cassert>
+
 namespace chatterino {
 namespace util {
 
@@ -12,13 +14,51 @@ struct EmoteData {
     }
 
     EmoteData(messages::LazyLoadedImage *_image)
-        : image(_image)
+        : image1x(_image)
     {
     }
 
-    messages::LazyLoadedImage *image = nullptr;
+    messages::LazyLoadedImage *getImageForSize(unsigned emoteSize) const
+    {
+        messages::LazyLoadedImage *ret = nullptr;
+
+        switch (emoteSize) {
+            case 0:
+                ret = this->image1x;
+                break;
+            case 1:
+                ret = this->image2x;
+                break;
+            case 2:
+                ret = this->image3x;
+                break;
+
+            default:
+                ret = this->image1x;
+                break;
+        }
+
+        if (ret == nullptr) {
+            ret = this->image1x;
+        }
+
+        assert(ret != nullptr);
+
+        return ret;
+    }
+
+    // Emotes must have a 1x image to be valid
+    bool isValid() const
+    {
+        return this->image1x != nullptr;
+    }
+
+    messages::LazyLoadedImage *image1x = nullptr;
+    messages::LazyLoadedImage *image2x = nullptr;
+    messages::LazyLoadedImage *image3x = nullptr;
 };
 
 typedef ConcurrentMap<QString, EmoteData> EmoteMap;
-}
-}
+
+}  // namespace util
+}  // namespace chatterino