1.0.11.22: hash-table synchronization support

1.0.11.22: hash-table synchronization support

* :SYNCHRONIZED argument to MAKE-HASH-TABLE.

* HASH-TABLE-SYNCHRONIZED-P predicate.

* WITH-LOCKED-HASH-TABLE for coarser locks.

* Additional MAPHASH & WITH-HASH-TABLE-ITERATOR documentation.

* :LOCKED argument added to DOHASH, and used where appropriate
  (some usages might be overly conservative, though, and could
  be removed.)