add support for old proxyAuthz encoding; allow to workaround buggy implementations of the new version (now RFC4370)

set it explicitly and handle its refcount.

actually, if a connection is already in the AVL tree, use it if not binding; otherwise use a tainted one; taint connections that must be freed when refcnt goes to zero

Move TLS options into struct ldapoptions.
  Added ldap_int_tls_destroy()
  Added LDAP_OPT_X_TLS_NEWCTX to generate new SSL_CTX

ch_ routines, not SLAP_ macros