Exe only patch

This fixes up the branch referenced by #904, so it no longer suffer from merge conflicts.

More importantly -- I'm not super comfortable about changing the default behavior of the VBS, ASP, and ASPX wrappers for the exe generators, mainly because I haven't seen anything compelling that says that these mechanisms should favor this new method.

When exe-small was introduced, these wrappers weren't updated to use them. Maybe it was an oversight, and maybe it was caution.

I think that kind of investigation should happen for sure, and then default behavior can get changed around. In the meantime, for people who want to use this payload type, they still can (as @rsmudge did in his examples).

So, tl;dr: more testing to prove that the AV evasion benefits are actually there, and more testing to prove that the wrappers aren't suddenly busted, if you please.