...to limit confusion and keep URLs-as-identifiers consistent over time. requested by @aaronpk since some people change the links in the profiles often and he wants to be able to identify them over time. IRC discussion.

conclusion is to put both silo and profile URLs into p-author, but always put silo URL first.

(also bridgy seems inconsistent? it might prefer profile links for replies/comments but silo URL for likes? need to investigate.)