#22 Create "dkim_method", "domainkeys_method" options

[Jason Long]

For each of the main signing options, keyfile, selector, algorithm, and method (and domain and identity?), create additional options prefixed with domainkeys_ and dkim_ that will apply only for that signature type.

E.g. so instead of having to say "dkim(c=relaxed,a=rsa_sha256),domainkeys(c=nofws)" in the sender map file, I could specify --dkim_method=relaxed --dkim_algorithm=rsa_sha256 --domainkeys_method=nofws in the main config file, and then simply specify "dkim,domainkeys" in the sender map file.

Note: there is not currently an "algorithm" option. Since domainkeys only supports one algorithm, perhaps I can simply implement a dkim_algorithm option and not worry about making an "algorithm" option.

[Jason Long]

support for dkim_method, domainkeys_method is now in SVN