This update fixes the big issue of stacking not always working. This was a really simple mistake that I managed to overlook...

• Stacker doesn't work (#12)
• Prevent Armour Stands from stacking (#15)
• Fix IllegalArgumentException when statistics are increased.
• Prevent the death step from being bigger than the entity stack size, so more drops than should be are dropped.
• Fixed the tagmode of stacks not being checked so the display tag would disappear regardless of the config option.