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/timelinewidget/view/timelineviewghostitem.cpp

@@ -22,6 +22,8 @@
 
 #include <QPainter>
 
+OLIVE_NAMESPACE_ENTER
+
 TimelineViewGhostItem::TimelineViewGhostItem(QGraphicsItem *parent) :
   TimelineViewRect(parent),
   track_adj_(0),
@@ -211,3 +213,5 @@ void TimelineViewGhostItem::UpdateRect()
 
   setPos(TimeToScene(GetAdjustedIn()), 0);
 }
+
+OLIVE_NAMESPACE_EXIT