This uses a "VM tendency" system wherein the presence of `DoAction` or `DoInitAction` tags defaults the movie to AVM1, while the presence of `DoABC` defaults to AVM2. The presence of a `FileAttributes` tag allows setting the VM tendency in the same manner using it's AS3 bit.
Particularly malformed SWFs may cause execution issues if Flash Player uses a dramatically different system from this.
This requires the use of an intermediary enum called `AvmObject` which can hold either object representation. Currently, it's mostly just being unwrapped as AVM1 objects, which we will need to fix.
David Wendt