First implementation of ChangeNotify - this version only checks

First implementation of ChangeNotify - this version only checks
for changes in the directory modify timestamps. A better version
will look at the requested client flags, and create a hash that
represents the current state of the directory, and check against
this instead.
debug.c: Added lp_timestamp_logs() function.
loadparm.c: Added "change notify timeout" in seconds (default 60)
- this is the scan rate for a directory.
            Added ""timestamp logs" boolean - default True. Turns
off log timestamps (so I can read them :-).
nttrans.c: ChangeNotify implementation.
server.c: ChangeNotify implementation.
shmem_sysv.c: Added exits on shmem errors (without them smbd can
              core dump if some calls fail).
smb.h: Added ChangeNotify flags for future use.
util.c: Tidied up typedef.
Jeremy.