add config for salination plant water transformation per update

Partially addresses #1847

Adds a config to increase the amount of water a salination plant turns into brine per update. Increasing this value will make it so you need fewer plants to process the same amount of water into brine, while decreasing would increase the number of plants.

Once again, merge if this kind of config fits your vision. Also, if the storm of PRs is getting annoying, let me know and we can find a better way to do this (maybe I just keep to myself :stuck_out_tongue:).