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/timeline/timelinecoordinate.cpp

@@ -20,6 +20,8 @@
 
 #include "timelinecoordinate.h"
 
+OLIVE_NAMESPACE_ENTER
+
 TimelineCoordinate::TimelineCoordinate() :
   track_(Timeline::kTrackTypeNone, 0)
 {
@@ -56,3 +58,5 @@ void TimelineCoordinate::SetTrack(const TrackReference &track)
 {
   track_ = track;
 }
+
+OLIVE_NAMESPACE_EXIT