DOC
TODO: delete and remove item in PLTSBlock::take
VirtualArray::size() is now a private method
use capacity in virtual array instead of size

VirtualArray::push is not required anymore
clean up PLTSblocks if they do not return an active item when top() is called

Conflicts:
	pheet/ds/StrategyTaskStorage/ParetoLocality/ParetoLocalityTaskStoragePlace.h
TODO: free VirtalArray when PLTSBlock doesn't contain any active items anymore