+PH/17 A further patch from the Sieve maintainer: "Introduce the new Sieve
+ extension "envelope-auth". The code is finished and in agreement with
+ other implementations, but there is no documentation so far and in fact,
+ nobody wrote the draft yet. This extension is currently #undef'ed, thus
+ not changing the active code.
+
+ Print executed "if" and "elsif" statements when debugging is used. This
+ helps a great deal to understand what a filter does.
+
+ Document more things not specified clearly in RFC3028. I had all this
+ sorted out, when out of a sudden new issues came to my mind. Oops."
+