protocol: unify client changegroup methods

protocol: convert some ssh abort calls

protocol: clean up call-like functions in http and ssh clients

protocol: unify stream_out client code

protocol: unify basic http client requests

protocol: move basic ssh client commands to wirerepository

protocol: unify stream_out command

protocol: unify changegroup commands - add sendchangegroup protocol helpers - handle commands with None results - move changegroup commands into wireproto.py

protocol: add proto to method prototypes

protocol: use new wireproto infrastructure in ssh - add protocol helper - insert wireproto into dispatcher - drop duplicate functions from hgweb implementation

protocol: introduce wireproto.py - add a protocol-independent dispatcher - move most of the basic commands from sshserver to wireproto - dispatch through wireproto first

protocol: move most ssh responses to returns

protocol: add ssh getargs - introduce getargs - make getarg a helper function - update users

discovery: remove duplication for new remote head discovery