exchange: fix changeset pulling over http http compress its stream. The were building a bogus stream where the first 10 bytes where uncompressed. Confusing the client.

simple4server: update "from <changeset>" statement Could obviously not do it in the same changeset than the original changes.

exchange: properly wrap wireprotocol capabilities Just wrapping the module function only works for ssh. Ssh gets capability through the `hello` command. We also need to wrap the function stored in the command dict. This fix discovery for http peer.

simple4server: add origin and documentation to most function