Add storage capacity slider bar to conveyor loader

[yoakenashi]

Currently the storage bin and the smart storage bin have sliders that set the maximum capacity of the bin from 20,000 kg to any value, including 1 kg (great, love it):

But the conveyor loaders do not. The conveyor loader is fixed at 1,000 kg. I suggest that the storage capacity slider be added to the conveyor loader.

The reason why I suggest this is to simplify minimum resource transportation. The only example I have at the moment is for egg transportation. If I have a stable full of 2 creatures and 6 eggs, when the 7th egg is laid, the auto sweeper will vacuum up all 7 of the eggs and place them in the conveyor loader and transported away. If I could set the conveyor loader to 1 kg, only one egg would be moved to the conveyor loader and transported away, leaving the ideal count of 6 eggs.

An annoying work around is to set up a storage bin plus another auto sweeper to move only 1 egg to the storage bin, and then the second auto sweeper would move the one egg to the conveyor loader, but this means that the area of effects for the sweepers must be exactly correct, which is difficult in very tight areas.