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/input.h

@@ -25,6 +25,8 @@
 #include "keyframe.h"
 #include "param.h"
 
+OLIVE_NAMESPACE_ENTER
+
 /**
  * @brief A node parameter designed to take either user input or data from another node
  */
@@ -388,4 +390,6 @@ private slots:
 
 };
 
+OLIVE_NAMESPACE_EXIT
+
 #endif // NODEINPUT_H