otioload: Add simple dialog to change settings

Adds a table of sequences in the OTIO file and allows the settings to
be changed. The dialog takes a list of sequences and relies on each
OTIO timeline having a unique name.

The dialog has to be called from the main thread so there is a wrapper
function in Core.

app/dialog/otioproperties/otiopropertiesdialog.h

@@ -0,0 +1,39 @@
+
+#ifndef OTIOPROPERTIESDIALOG_H
+#define OTIOPROPERTIESDIALOG_H
+
+#include <QDialog>
+#include <QTreeWidget>
+
+#include "common/define.h"
+#include "opentimelineio/timeline.h"
+#include "node/project/sequence/sequence.h"
+#include "node/project/project.h"
+
+namespace olive {
+
+  /**
+   * @brief Dialog to load setting for OTIO sequences.
+   *
+   * Takes a list of Sequences and allows the setting of options for each.
+   */
+  class OTIOPropertiesDialog : public QDialog {
+    Q_OBJECT
+   public:
+    OTIOPropertiesDialog(QList<Sequence*> sequences, Project* active_project, QWidget* parent = nullptr);
+
+   private:
+    QTreeWidget* table_;
+
+    QList<Sequence*> sequences_;
+
+   private slots:
+    /**
+     * @brief Brings up the Sequence settings dialog.
+     */
+    void SetupSequence();
+  };
+
+} //namespace olive
+
+#endif  // OTIOPROPERTIESDIALOG_H