core_rpc_server_command_parser order

[jagerman]

RPC argument parsing (on dev) is currently doing things like this:

    get_values(in, "host", set_bans.request.host);
    get_values(in, "ip", set_bans.request.ip);
    get_values(in, "seconds", set_bans.request.seconds);
    get_values(in, "ban", set_bans.request.ban);

But this is broken because parsing has to happen in alphabetical order (because we support bt-encoded RPC, where we consume arguments, but arguments have to always be sorted).

Aside from the ordering, get_values is meant to take a list of all (or many) options at once, like this:

    get_values(in,
        "ban", set_bans.request.ban,
        "host", set_bans.request.host,
        "ip", set_bans.request.ip,
        "seconds", set_bans.request.seconds);

aside from being slightly cleaner syntax, this will also catch (at runtime) the out-of-order keys and raise an exception.