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/projectexplorer/projectexplorerundo.cpp

@@ -22,7 +22,7 @@
 
 namespace olive {
 
-OfflineFootageCommand::OfflineFootageCommand(const QList<MediaInput *> &media, QUndoCommand* parent) :
+OfflineFootageCommand::OfflineFootageCommand(const QVector<MediaInput *> &media, QUndoCommand* parent) :
   UndoCommand(parent)
 {
   foreach (MediaInput* i, media) {