[0.15] Miners should balance acid with connected pipes

[Hexicube]

Currently miners only share acid with other directly touching miners, which forces players to use a specific miner layout. Not everyone wants to use this layout, and using layouts that we prefer to use forces us to connect every miner separately.

Here's an example of a setup that I'd like to work with acid sharing: http://i.imgur.com/mvDt1xa.png
With the current mechanics, only the right two miners will get fed.

0.15 boilers already have pass-through water, so it should be possible to apply the same thing to miners.