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/scrollbarhighlight.cpp

@@ -1,14 +1,17 @@
 #include "widgets/scrollbarhighlight.hpp"
 #include "colorscheme.hpp"
+#include "widgets/scrollbar.hpp"
 
 namespace chatterino {
 namespace widgets {
 
-ScrollBarHighlight::ScrollBarHighlight(float position, int colorIndex, Style style, QString tag)
-    : _style(style)
-    , _position(position)
-    , _colorIndex(std::max(0, std::min(ColorScheme::getInstance().HighlightColorCount, colorIndex)))
-    , _tag(tag)
+ScrollBarHighlight::ScrollBarHighlight(double _position, int _colorIndex, ScrollBar *parent,
+                                       Style _style, QString _tag)
+    : colorScheme(parent->colorScheme)
+    , position(_position)
+    , colorIndex(std::max(0, std::min(this->colorScheme.HighlightColorCount, _colorIndex)))
+    , style(_style)
+    , tag(_tag)
 {
 }