Support for CHM to detect
Support for CHM to detect

Adding support for ```*.chm``` to detect. It is also rather popular way to deliver malware.

https://blog.rootshell.be/2017/12/19/malware-delivered-via-compiled-html-help-file/

MIME for CHM: https://mediatemple.net/community/products/dv/204403964/mime-types
IANA: http://www.iana.org/assignments/media-types/application/vnd.ms-htmlhelp
stamparm/maltrail,stamparm/maltrail,stamparm/maltrail,stamparm/maltrail