fix: an iterator won't point to the same item after a merge or repartition
always use iterators to access the virtual array
clean up partition pointer/iterator usage im block
DOC, clean up some todos
swap all tasks in old dead partition to new dead partition when merging
do not try to partition with same pivot element after falling back
pass left iterator when accessing random elements for pivot generation
Splice out blocks of virtual array if all items are dead
avoid using iterator_to
StrategyMspStrategy is not required in the abstract MSP task
remove debug code
remove omnious compiler flag
fix gcc issue
use 30 repetitions for benchmarking per default