flashproxy-client needs to pass args to reg-methods
At the moment it's not possible to (e.g.) give an email address to flashproxy-client for use in reg-email.
One possibility is to have args like --reg-email-arg=x --reg-email-arg=y
then [x, y] gets passed as args to reg-email. This is similar to what I have implemented in obfs-flash, where --fp-arg=x
gets passed to flashproxy-client.