finalized very, very basic OTIO support

Ironed out various project and footage loading issues, and a single
cache invalidation issue.

app/render/playbackcache.h

@@ -39,24 +39,16 @@ public:
   {
   }
 
-  void Invalidate(const TimeRange& r);
-
-  void InvalidateAll();
-
   const rational& GetLength()
   {
     return length_;
   }
 
-  void SetLength(const rational& r);
-
   bool IsFullyValidated()
   {
     return invalidated_.isEmpty();
   }
 
-  void Shift(const rational& from, const rational& to);
-
   const TimeRangeList& GetInvalidatedRanges()
   {
     return invalidated_;
@@ -69,6 +61,15 @@ public:
 
   QString GetCacheDirectory() const;
 
+public slots:
+  void Invalidate(const TimeRange& r);
+
+  void InvalidateAll();
+
+  void SetLength(const rational& r);
+
+  void Shift(const rational& from, const rational& to);
+
 signals:
   void Invalidated(const OLIVE_NAMESPACE::TimeRange& r);