Fighting the good fight. Move libfmt, libutf into subdirectories of lib9. Add poll-based socket i/o to libthread, so that we can avoid using multiple procs when possible, thus removing dependence on crappy pthreads implementations. Convert samterm, acme to the single-proc libthread. Bring libcomplete, acme up-to-date w.r.t. Plan 9 distribution.

various tweaks.

make -> mk remove clumsy stack hack. fix exec. fix nthreads maintenance. fix threadexitsall not to kill self. add sun support.