Updated memcached docs to reflect new memcached 2.X behavior.

- Added new Runtime Configuration directives.
- Updated libmemcached version requirements and new configuration options.
- Added new memcached 2.0 methods to Memcached class:
    * deletemulti
    * deletemultibykey
    * getallkeys
    * touchbykey
    * touch
    * incrementbykey
    * decrementbykey
    * ispersistent
    * ispristine
    * setsaslauthdata
    * setoptions
    * resetserverlist
    * quit

Modified fixes and modifications to reflect ChangeLog.

Path provided by David Terei (davidterei@gmail.com).


git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@329008 c90b9560-bf6c-de11-be94-00142212c4b1