annotate hex values for 9p message types it's a bit easier to debug hexdumps now

9pclib: fix qid serialization twstat was serializing the qid in the wrong order. While here, add a comment before the qid definition too.

wstat: missing read for size 9p stat message have a leading 2 bytes long size field. It's meant to simplify the parsing, because while reading the contents of a directory it's necessary to know how much long an entry is, so the length field is present even in the Rstat reply and in the Twstat input. Previously we didn't consume that bit and thus mis-read all of the following fields.

move struct np_stat to kami.h

restructure project and switch build system use by default the OpenBSD mk infrastructure to build and test all the kamid components.