Move gif timer stuff to its own class

Clean up unused includes

src/messages/image.cpp

@@ -125,7 +125,7 @@ void Image::loadImage()
         if (this->allFrames.size() > 1) {
             if (!this->animated) {
                 util::postToThread([this] {
-                    getApp()->emotes->getGifUpdateSignal().connect([=]() {
+                    getApp()->emotes->gifTimer.signal.connect([=]() {
                         this->gifUpdateTimout();
                     });  // For some reason when Boost signal is in
                          // thread scope and thread deletes the signal