A lot of changes

Remove unused constructor of messages::Message
Fixed LimitedQueueSnapshot _-prefixes
Changed LimitedQueueSnapshot's usage of int to std::size_t
ColorScheme is no longer a singleton
Created a "BaseWidget" class which is pretty much a QWidget except it
has a reference of ColorScheme since most widgets will need a reference
to the style they should use.
BaseWidget can be implemented either with a BaseWidget parent (which
will copy the ColorScheme reference from the parent) or with a
normal QWidget parent and an explicit ColorScheme reference.
Save main window geometry on close
Fix font changing in the Settings Dialog
Update settings library version

src/widgets/chatwidgetview.hpp

@@ -5,6 +5,7 @@
 #include "messages/messageref.hpp"
 #include "messages/word.hpp"
 #include "widgets/accountpopup.hpp"
+#include "widgets/basewidget.hpp"
 #include "widgets/scrollbar.hpp"
 
 #include <QPaintEvent>
@@ -17,7 +18,7 @@ namespace widgets {
 
 class ChatWidget;
 
-class ChatWidgetView : public QWidget
+class ChatWidgetView : public BaseWidget
 {
 public:
     explicit ChatWidgetView(ChatWidget *_chatWidget);