test to check that partition operation terminates. TODO: strange SIGILL caused by future
ref: split put()

one method top ensure put() is called on lvl 0 blocks only; another for internal testing purposes
block::size is not needed
get nr dimensions from strategy

instead of hard coded value
do not allow two equal PivotElements on PivotQueue
limit the attempts to generate a unique pivot element
limit partition operations that do not reduce the size of the block that still needs to be partitioned