various: encapsulate all code in the olive namespace to avoid name collisions

Large-scale code cleanup. Also adds a license to the top of all files that were
missing it.

app/node/output/viewer/viewer.h

@@ -32,6 +32,8 @@
 #include "render/audioparams.h"
 #include "timeline/trackreference.h"
 
+OLIVE_NAMESPACE_ENTER
+
 /**
  * @brief A bridge between a node system and a ViewerPanel
  *
@@ -143,4 +145,6 @@ private slots:
 
 };
 
+OLIVE_NAMESPACE_EXIT
+
 #endif // VIEWER_H