began new infrastructure

Yep, this is another one of my "famous" sweeping rewrites. Expect things to break.

Goals for this are:
- Greatly simplify node connections (particularly with arrays) so the code requires less maintenance/is more stable
- Redesign node structure to address issues where UI would stall for lengthy periods of time
- Less reliance on shared ptrs/greater reliance on QObject system for inheritance/memory management
- General code cleanup and improvements

app/widget/nodeview/nodeviewcommon.h

@@ -1,58 +0,0 @@
-/***
-
-  Olive - Non-Linear Video Editor
-  Copyright (C) 2020 Olive Team
-
-  This program is free software: you can redistribute it and/or modify
-  it under the terms of the GNU General Public License as published by
-  the Free Software Foundation, either version 3 of the License, or
-  (at your option) any later version.
-
-  This program is distributed in the hope that it will be useful,
-  but WITHOUT ANY WARRANTY; without even the implied warranty of
-  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-  GNU General Public License for more details.
-
-  You should have received a copy of the GNU General Public License
-  along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-***/
-
-#ifndef NODEVIEWCOMMON_H
-#define NODEVIEWCOMMON_H
-
-#include <QtGlobal>
-
-#include "common/define.h"
-
-namespace olive {
-
-class NodeViewCommon {
-public:
-  enum FlowDirection {
-    kTopToBottom,
-    kBottomToTop,
-    kLeftToRight,
-    kRightToLeft
-  };
-
-  static Qt::Orientation GetFlowOrientation(FlowDirection dir) {
-    if (dir == kTopToBottom || dir == kBottomToTop) {
-      return Qt::Vertical;
-    } else {
-      return Qt::Horizontal;
-    }
-  }
-
-  static bool DirectionsAreOpposing(FlowDirection a, FlowDirection b) {
-    return ((a == NodeViewCommon::kLeftToRight && b == NodeViewCommon::kRightToLeft)
-            || (a == NodeViewCommon::kRightToLeft && b == NodeViewCommon::kLeftToRight)
-            || (a == NodeViewCommon::kTopToBottom && b == NodeViewCommon::kBottomToTop)
-            || (a == NodeViewCommon::kBottomToTop && b == NodeViewCommon::kTopToBottom));
-  }
-
-};
-
-}
-
-#endif // NODEVIEWCOMMON_H