Support Macro detection

[yippibrian]

It would be useful if there were a function to simply identify when Macros are present. This way this library could be used to help reject documents that are uploaded that contain macros, for security reasons.

This OWASP page discusses how to do this in Java: https://www.owasp.org/index.php/Protect_FileUpload_Against_Malicious_File

Note this is not a request to support macros beyond being able to identify if a macro is present.