Log Message:
Update to 1.0.12. From the changelog:

* WritableDatabase::remove_spelling() now works properly.
* The QueryParser now treats NON_SPACING_MARK Unicode characters as phrase
  generators, which improves handling of Arabic.  This is a stop-gap solution
  for 1.0.x which will work with existing databases without requiring
  reindexing - in 1.1.0, NON_SPACING_MARK will be regarded as part of a word.
  (ticket#355)
* Fix undefined behaviour in distribution of OP_NEAR and OP_PHRASE over a
  non-leaf subquery (indentified by valgrind on testcase nearsubqueries1).
  (ticket#349)
* Enhance distribution of OP_NEAR/OP_PHRASE over non-leaf subqueries to work
  when there are multiple non-leaf subqueries (ticket#201).
* Enquire::get_mset() no longer needlessly checks if the documents exist.
* PostingIterator::get_description() output improved visually in some cases.
* Enquire::get_mset():
  + Now throws UnimplementedError if there's a percentage cutoff and sorting is
    primarily by value - this has never been correctly supported and it's
    better to warn people than give incorrect results.
  + No longer needlessly copies the results internally.
  + When searching multiple databases, now recalculates the maximum attainable
    weight after each database which may allow it to terminate earlier.
    (ticket#336).
  + Fix inconsistent percentage scores when sorting primarily by value, except
    when a MatchDecider is also being used; document this remaining problem
    case.  (ticket#216)
* Enquire::set_sort_by_value() (and similar methods): Rename the wrongly named
  "ascending" parameter to "reverse", and note that its \ 
value should always be
  explicitly given since defaulting to "reverse=true" is confusing and the
  default will be deprecated in 1.1.0.  (ticket#311)
* Database::allterms_begin(): Fix memory leak when iterating all terms from
  more than one database.
* Query::get_terms_begin(): Don't return "" from the TermIterator (happened
  when the query contained or was Query::MatchAll).
* Add QueryParser::FLAG_DEFAULT to make it easier to add flags to those set by
  default.