remote plugin patch for netqmail-1.06

Greetings.

I made a patch that allows it to execute programs before qmail-remote 
will be invoked. The function can be compared with Bruce Guenter's 
qmailqueue.patch, because it allows to add program(s) into the 
qmail-rspawn->qmail-remote pipeline. As an example - and like I use it - 
there can be done DKIM signing. It is part of my upcoming eQmail-1.09 
package and was extracted to have a lowest common denominator.

Download: 
ftp://ftp.dyndn.es/openqmail/netqmail-1.06-before-remote.patch.tgz

sha256sum: 
f1d1826dcc960173041c150558d2c7c871ae6f6b7073a54e08ce88a5655dc3ba  
(ftp://ftp.dyndn.es/openqmail/netqmail-1.06-before-remote.patch.tgz.sha256)

The patch will be discussed at the openqmail mailing list: 
[email protected]

A bit more documentation is available at 
https://blog.dyndn.es/doku.php/blog/2016/02/01_netqmail-bfrmt.

regards
Kai