Fix preview on hover not working when Animated emotes options was disabled.

Fixes #1546

This change introduces a "window timer" that runs every 100ms that we
use to update the pixmap if necessary, since there is no signal for "let
me know when this image is done loading".

src/singletons/WindowManager.hpp

@@ -80,6 +80,10 @@ public:
 
     pajlada::Signals::NoArgSignal wordFlagsChanged;
 
+    // This signal fires every 100ms and can be used to trigger random things that require a recheck.
+    // It is currently being used by the "Tooltip Preview Image" system to recheck if an image is ready to be rendered.
+    pajlada::Signals::NoArgSignal miscUpdate;
+
 private:
     void encodeNodeRecusively(SplitContainer::Node *node, QJsonObject &obj);
 
@@ -96,6 +100,7 @@ private:
     pajlada::SettingListener wordFlagsListener_;
 
     QTimer *saveTimer;
+    QTimer miscUpdateTimer_;
 };
 
 }  // namespace chatterino