implemented basic animation curve editor widgets

Frontend is largely done, it just needs backend and connecting to other
widgets to function correctly.

app/panel/curve/curve.cpp

@@ -6,6 +6,10 @@ CurvePanel::CurvePanel(QWidget *parent) :
   // FIXME: This won't work if there's ever more than one of this panel
   setObjectName("CurvePanel");
 
+  // Create main widget and set it
+  widget_ = new CurveWidget();
+  setWidget(widget_);
+
   // Set strings
   Retranslate();
 }

app/panel/curve/curve.h

@@ -1,6 +1,7 @@
 #ifndef CURVEPANEL_H
 #define CURVEPANEL_H
 
+#include "widget/curvewidget/curvewidget.h"
 #include "widget/panel/panel.h"
 
 class CurvePanel : public PanelWidget
@@ -14,6 +15,8 @@ protected:
 private:
   void Retranslate();
 
+  CurveWidget* widget_;
+
 };
 
 #endif // CURVEPANEL_H