Fixed bugs introduced in first fix of #3

Ladder dispenser:
- Ladder retrieval did not work when inventory was empty.
- Insta-placed the same amount of ladders as slots occupied of same
type.
- When retracting ladders the dispenser would spit out ladders if a slot
had max limit of items, instead of going to next slot.
- (not introduced in #3) Dispenser "kept running" while redstone signal
were active, causing tick updates every 10 ticks. Now it properly "shuts
off" after placing all ladders it can place.

Also removed some unused libraries & functions + fixed sturdy ladder
creating rope ladder tile entity.