WL#1733: Handler: not "sorted ordered index

Not "sorted" ordered index.
  - New function get_bounded on handler, this will be called instead of 
index_first, index_last in opt_range.cc
  - Make it possible to return ordered indexes sorted by setting "sorted" flag 
when starting ordered index scan. Perform a merge sort in NdbApi.
  This will have to be used for MIN() and MAX() functions?!