Fracking,Water: Split Well into separate file in prep for sharing code
Fracking: Create split Gas specific well functionality into GasWell
Fracking: Move a lot of the drilling logic into the Well class
Rename GasWell file
Wells: Correctly stop before hitting the bottom of the model
Wells: Have the well set the well and wellWall patch colors
Wells: Use patchChanged instead of setPatchColor

It makes more sense since we're notifying the model that something about
the patch changed.
Water: Add well drilling
Water: Wells now remove water around their deepest point