implement entire project in nodes

Project items are now represented directly in nodes opening up more versatility and possibilities. This is the first iteration of this and will be buggy. Need to test thoroughly.

app/render/stillimagecache.h

@@ -5,7 +5,7 @@
 #include <QWaitCondition>
 
 #include "common/rational.h"
-#include "project/item/footage/videostream.h"
+#include "project/item/footage/footage.h"
 #include "render/texture.h"
 
 namespace olive {
@@ -14,7 +14,7 @@ class StillImageCache
 {
 public:
   struct Entry {
-    Entry(TexturePtr t, VideoStream* s, const QString& cs, bool a, int d, const rational& i, bool w)
+    Entry(TexturePtr t, const Footage::StreamReference& s, const QString& cs, bool a, int d, const rational& i, bool w)
     {
       texture = t;
       stream = s;
@@ -26,7 +26,7 @@ public:
     }
 
     TexturePtr texture;
-    VideoStream* stream;
+    Footage::StreamReference stream;
     QString colorspace;
     bool alpha_is_associated;
     int divider;