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/chatwidget.hpp

@@ -5,6 +5,7 @@
 #include "messages/messageref.hpp"
 #include "messages/word.hpp"
 #include "messages/wordpart.hpp"
+#include "widgets/basewidget.hpp"
 #include "widgets/chatwidgetheader.hpp"
 #include "widgets/chatwidgetinput.hpp"
 #include "widgets/chatwidgetview.hpp"
@@ -19,9 +20,12 @@
 namespace chatterino {
 
 class ChannelManager;
+class ColorScheme;
 
 namespace widgets {
 
+class NotebookPage;
+
 // Each ChatWidget consists of three sub-elements that handle their own part of the chat widget:
 // ChatWidgetHeader
 //   - Responsible for rendering which channel the ChatWidget is in, and the menu in the top-left of
@@ -32,12 +36,12 @@ namespace widgets {
 //   - Responsible for rendering and handling user text input
 //
 // Each sub-element has a reference to the parent Chat Widget
-class ChatWidget : public QWidget
+class ChatWidget : public BaseWidget
 {
     Q_OBJECT
 
 public:
-    ChatWidget(ChannelManager &_channelManager, QWidget *parent = nullptr);
+    ChatWidget(ChannelManager &_channelManager, NotebookPage *parent);
     ~ChatWidget();
 
     std::shared_ptr<Channel> getChannel() const;