variable in counter add_diversion

[Edwin-Hoff]

Feature request:
use a variable as counter parameter in the add_diversion function

Right now the add_diversion() does not support variables in parameters:
add_diversion(reason [[,uri], counter])
counter - Diversion counter to be added to the header, as defined by the standard.

I would like to use the function like this:
add_diversion("unconditional;privacy=id;screen=no","sip:anonymous@anonymous.invalid","$avp(mydiversioncounter");