Misc cleanup

  "ABANDON", "STARTTLS", "CANCEL", "WHOAMI", "PASSMOD", "EXT", "INTERM",
  "TLS established", SASL and Extended Response "RESULT".
In Statslog output "conn=xx fd=yy closed", append the reason in
  "()" unless client or server closed the connection after Unbind.
Still missing Statslog output from a number of failed requests.

consolidated into the Operation structure. All reply parameters
are consolidated into the new SlapReply structure. Most operations
now have identical call signatures... Changes are not #ifdef'd,
revert to -r NO_SLAP_OP_BLOCKS if necessary to back out.

for the known exops.

liblber:ber_bvarray_{add,free}.

conn->c_dn,c_ndn, Access->a_dn_pat)

Fix compile errors

need to rework cert check to use per lconn host name

Add "disallow tls_authc" to disallow StartTLS when session is authenticated.
Create and use connection2anonymous routine for consistency.

SASL mech removed from backend bind callback (as SASL is managed by frontend)
Changes to some backends are untested (as I don't have all dependent
  software install)