Player Interface getStackInSlot For Input Inventory && ME Bridge maxStackSize #158

Currently you can get information pertaining to an itemstack from the PlayerInventory object, but you can't do the same for the input inventory.

This is extremely useful for retrieval systems since there isn't an elegant way to test to see if a slot inside the Input inventory contains the item the player actually requested. With this implemented, you can then test each slot to see if the data matches the players requested and push the item in that slot to the players inventory.

Thanks.