Move all the things (YES. Move them.)

Also, implemented some basic modlist logic, to be wired up.

logic/LegacyInstance_p.h

@@ -0,0 +1,15 @@
+#pragma once
+#include <QString>
+#include <settingsobject.h>
+#include "BaseInstance_p.h"
+#include "ModList.h"
+#include <QSharedPointer>
+
+class ModList;
+
+struct LegacyInstancePrivate: public BaseInstancePrivate
+{
+	QSharedPointer<ModList> jar_mod_list;
+	QSharedPointer<ModList> core_mod_list;
+	QSharedPointer<ModList> loader_mod_list;
+};