This is a minor release to provide out-of-the-box compatibility with the merge
of libldap and libldap_r that happened with OpenLDAP's 2.5 release.

The following undocumented functions are deprecated and scheduled for removal:
- ``ldap.cidict.strlist_intersection``
- ``ldap.cidict.strlist_minus``
- ``ldap.cidict.strlist_union``

The following deprecated option has been removed:
- ``OPT_X_TLS``

Doc/
* SASL option usage has been clarified

Lib/
* ppolicy control definition has been updated to match Behera draft 11

Modules/
* By default, compile against libldap, checking whether it provides a
  threadsafe implementation at runtime
* When decoding controls, the module can now distinguish between no value
  (now exposed as ``None``) and an empty value (exposed as ``b''``)
* Several new OpenLDAP options are now supported:
  * ``OPT_SOCKET_BIND_ADDRESSES``
  * ``OPT_TCP_USER_TIMEOUT``
  * ``OPT_X_SASL_MAXBUFSIZE``
  * ``OPT_X_SASL_SECPROPS``
  * ``OPT_X_TLS_ECNAME``
  * ``OPT_X_TLS_PEERCERT``
  * ``OPT_X_TLS_PROTOCOL``-related options and constants

Fixes:
* Encoding/decoding of boolean controls has been corrected
* ldap.schema.models.Entry is now usable
* ``method`` keyword to ReconnectLDAPObject.bind_s is now usable