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/widget/projectexplorer/projectexplorerlistview.h

@@ -24,6 +24,8 @@
 #include "projectexplorerlistviewbase.h"
 #include "projectexplorerlistviewitemdelegate.h"
 
+OLIVE_NAMESPACE_ENTER
+
 /**
  * @brief The view widget used when ProjectExplorer is in List View
  */
@@ -37,4 +39,6 @@ private:
   ProjectExplorerListViewItemDelegate delegate_;
 };
 
+OLIVE_NAMESPACE_EXIT
+
 #endif // PROJECTEXPLORERLISTVIEW_H