1/ setuid is no-op
2/ (Quickly) Allow to compile with slapos.

Work on mail_params.c, master.c, postsuper.c by Marco Mariani.

Update user to use the command form, as it properly handles an existing
LD_PRELOAD variable internally.

Update users.

Implemented using libuserhosts. Only provided to zope processes so far, may be
extended in the future with each process seeing different sets of aliases,
with potentially different resolutions.

Also, do not tolerate missing instance-count internal zope partition
parameter.

also build with our own ncurses instead of system termcap library.

  All software releases which are consider unstable and not mantained were
 moved to "unstable" folder. This folder is aims to be the place for tests,
 experimentation, personal releases which are not updated or tested for long
 term support.

also explicitly use our own giflib and libtiff.

so that we don't need to differentiate software/erp5/software.cfg in erp5-component branch.

zc.buildout >= 1.6.0-dev-SlapOS-013 automatically rebuilds parts whose referring parts are modified.