Remove optional arguments usage in AVM1 interpreter

We can easily guarantee that all callsites do the right thing here, and optional arguments have a runtime overhead.
Warn whenever AVM1 just swallows an invalid operation

We used to, incorrectly, throw errors on these operations. Flash doesn't, so we don't, anymore. At least, we should warn to aid our own debugging, if nothing else.
Change AVM1 ActionNewObject to ignore non-function targets

As per spec and Flash's behavior, not sanity.
Change AVM1 enumeration to ignore undefined targets

As per spec and Flash's behavior, not sanity.
Merge pull request #1443 from tschneidereit/nat

Warn instead of throwing on more AVM1 actions