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/dialog/projectproperties/projectproperties.h

@@ -27,6 +27,8 @@
 
 #include "project/project.h"
 
+OLIVE_NAMESPACE_ENTER
+
 class ProjectPropertiesDialog : public QDialog
 {
   Q_OBJECT
@@ -52,4 +54,6 @@ private slots:
 
 };
 
+OLIVE_NAMESPACE_EXIT
+
 #endif // PROJECTPROPERTIESDIALOG_H