Sieve's editheader extension in managesieve plugin

[rabudde]

I'm using Dovecot 2.1.3 with Pigeonhole 0.3 and Roundcube 0.7.1 but I'm missing filter settings for editheader extension of Sieve. Because we want to setup a notification server (so this request is of high importance for us) that examines mail headers it would be great if I can administrate Sieve via Roundcube by using Sieve's internal editheader extension (http://tools.ietf.org/html/rfc5293).