We now use ints, and hopefully this means we don't have as much obvious
stuff in the binaries!
```
$ # Before:
$ strings metsrv.x86.dll | grep core_ | wc -l
46
$ # After:
$ strings metsrv.x86.dll | grep core_ | wc -l
0
```
Big win, and it's even bigger for the likes of stdapi.
Had to fix a bunch of other stuff along the way, including a subtle
issue with the Powershell Meterp bindings.
This updates the packet header so that the encryption byte flag is now
32 bits. This also updates the powershell and python extensions so that
both of the bindings work correctly as a result of the TLV packet header
changes.
