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/mainwindow.hpp

@@ -11,6 +11,9 @@
 #include <boost/property_tree/ptree.hpp>
 
 namespace chatterino {
+
+class ChannelManager;
+
 namespace widgets {
 
 class MainWindow : public QWidget
@@ -18,7 +21,7 @@ class MainWindow : public QWidget
     Q_OBJECT
 
 public:
-    explicit MainWindow(QWidget *parent = 0);
+    explicit MainWindow(ChannelManager &_channelManager, QWidget *parent = nullptr);
     ~MainWindow();
 
     void layoutVisibleChatWidgets(Channel *channel = nullptr);
@@ -34,7 +37,9 @@ public:
     Notebook &getNotebook();
 
 private:
-    Notebook _notebook;
+    ChannelManager &channelManager;
+
+    Notebook notebook;
     bool _loaded;
     TitleBar _titleBar;
 };