ui: added universal font size setting and shortcuts for changing it

This change adds font size and font family to the ApplicationSettings to have a single point for manipulating them. The
font size can also be changed via the menu or the zoomIn and zoomOut shortcuts on all platforms.

src/lib/utility/messaging/type/MessageRefresh.h

@@ -6,7 +6,8 @@
 class MessageRefresh: public Message<MessageRefresh>
 {
 public:
-	MessageRefresh()
+	MessageRefresh(bool uiOnly = false)
+		: uiOnly(uiOnly)
 	{
 	}
 
@@ -14,6 +15,8 @@ public:
 	{
 		return "MessageRefresh";
 	}
+
+	const bool uiOnly;
 };
 
 #endif // MESSAGE_REFRESH_H

src/lib/utility/messaging/type/MessageZoom.h

@@ -0,0 +1,23 @@
+#ifndef MESSAGE_ZOOM_H
+#define MESSAGE_ZOOM_H
+
+#include "utility/messaging/Message.h"
+
+class MessageZoom
+	: public Message<MessageZoom>
+{
+public:
+	MessageZoom(bool zoomIn)
+		: zoomIn(zoomIn)
+	{
+	}
+
+	static const std::string getStaticType()
+	{
+		return "MessageZoom";
+	}
+
+	const bool zoomIn;
+};
+
+#endif // MESSAGE_ZOOM_H