Move OTIO macro to define.h

Move the OTIO macro to define.h to avoid having to add it to all
required files.

Also add some cleanup.

app/common/define.h

@@ -27,6 +27,8 @@
 
 #define OLIVE_NAMESPACE_EXIT }
 
+#define OTIO opentimelineio::OPENTIMELINEIO_VERSION
+
 OLIVE_NAMESPACE_ENTER
 
 const int kHSVChannels = 3;