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/basewidget.hpp

@@ -1,4 +1,34 @@
-#ifndef BASEWIDGET_HPP
-#define BASEWIDGET_HPP
+#pragma once
 
-#endif // BASEWIDGET_HPP
+#include "colorscheme.hpp"
+
+#include <QWidget>
+
+namespace chatterino {
+
+class ColorScheme;
+
+namespace widgets {
+
+class BaseWidget : public QWidget
+{
+    Q_OBJECT
+
+public:
+    explicit BaseWidget(ColorScheme &_colorScheme, QWidget *parent)
+        : QWidget(parent)
+        , colorScheme(_colorScheme)
+    {
+    }
+
+    explicit BaseWidget(BaseWidget *parent)
+        : QWidget(parent)
+        , colorScheme(parent->colorScheme)
+    {
+    }
+
+    ColorScheme &colorScheme;
+};
+
+}  // namespace widgets
+}  // namespace chatterino