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/node/connectable.cpp

@@ -0,0 +1,77 @@
+/***
+
+  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/>.
+
+***/
+
+#include "connectable.h"
+
+#include "input.h"
+#include "node.h"
+
+namespace olive {
+
+void NodeConnectable::ConnectEdge(Node *output, NodeInput *input, int element)
+{
+  InputConnection conn_to_in = {input, element};
+
+  // Connection exists
+  if (output->output_connections_.contains(conn_to_in)) {
+    qDebug() << "Ignored connect that already exists";
+    return;
+  }
+
+  // Ensure a connection isn't getting overwritten
+  Q_ASSERT(!input->input_connections_.contains(element));
+
+  // Insert connections in both sides
+  output->output_connections_.append(conn_to_in);
+  input->input_connections_.insert(element, output);
+
+  // Emit signals
+  emit input->InputConnected(output, element);
+  emit output->OutputConnected(input, element);
+}
+
+void NodeConnectable::DisconnectEdge(Node *output, NodeInput *input, int element)
+{
+  InputConnection conn_to_in = {input, element};
+
+  // Connection exists
+  if (!output->output_connections_.contains(conn_to_in)) {
+    qDebug() << "Ignored disconnect that doesn't exist";
+    return;
+  }
+
+  // Assertions to ensure connection exists
+  Q_ASSERT(input->input_connections_.value(element) == output);
+
+  // Remove connections from both sides
+  output->output_connections_.removeOne(conn_to_in);
+  input->input_connections_.remove(element);
+
+  // Emit signals
+  emit input->InputDisconnected(output, element);
+  emit output->OutputDisconnected(input, element);
+}
+
+uint qHash(const NodeConnectable::InputConnection &r, uint seed)
+{
+  return ::qHash(r.input, seed) ^ ::qHash(r.element, seed);
+}
+
+}