Huge refactor

- Remove some underscore-prefixes
 - Start using this-> more
 - Remove a few of the singletons (We pass references to managers to
         things that need it now. Might not be much better, but for now
         it works. It also shows what places might be slightly wrong
         designed)

src/widgets/chatwidget.hpp

@@ -17,6 +17,9 @@
 #include <boost/signals2/connection.hpp>
 
 namespace chatterino {
+
+class ChannelManager;
+
 namespace widgets {
 
 // Each ChatWidget consists of three sub-elements that handle their own part of the chat widget:
@@ -34,7 +37,7 @@ class ChatWidget : public QWidget
     Q_OBJECT
 
 public:
-    ChatWidget(QWidget *parent = nullptr);
+    ChatWidget(ChannelManager &_channelManager, QWidget *parent = nullptr);
     ~ChatWidget();
 
     std::shared_ptr<Channel> getChannel() const;
@@ -53,6 +56,8 @@ protected:
     void paintEvent(QPaintEvent *) override;
 
 private:
+    ChannelManager &channelManager;
+
     void setChannel(std::shared_ptr<Channel> newChannel);
     void detachChannel();