Client enhancements to get crtime, file magic, and PE headers data

I used MSYS2 with MINGW to build libgnurx-0.dll and magic1.dll for Windows to be able to properly use python-magic.  The installer would also need to be modified to include the file magic database magic.mgc in the client installed directory.

I removed some packing detection and checksum comparison due to it having a pretty significant performance hit on larger binaries.  It may be worth it to enable those via options when a flow is run.

This also carves off the PKCS7 certs on PE files and returns them.  There might be better ways to do this.
I don't think we want to log MagicException. It's only really useful in debugging anyway since it will likely be very common (we regularly stat millions of files in a hunt). If you're interested in the files that failed magic checking you could build a list of files retrieved that didn't have magic set on the server and hunt for them.