[Serusers] sequential forking support

[Juha Heinanen]

i just committed some patches to lcr module that introduced two new
functions: load_contacts() and next_contacts().  they can be used to
implement sequential forking (see README for details).  

if all contacts in the destination set have the same qvalue,
load_contacts() and next_contacts() don't do anything, just check that
nothing needs to be done.

-- juha