zfromx: Determine Bottom Depth from Easting
In JVAdams/artiFISHal: A Pelagic Fish Community Simulator

Determine the distance to the bottom from a given easting.

1	zfromx(x, maxz, eastr, ints, slopes)

`x`	A numeric vector of the eastings to convert (in m).
`maxz`	A numeric scalar, the maximum bottom depth of the lake (in m).
`eastr`	A numeric vector of length 2, easting range (minimum and maximum) corresponding to the west and east shores of the lake (in m).
`ints`	A numeric vector of length 2, the intercepts of the angled lake beds along the west and east shores of the lake (in m).
`slopes`	A numeric vector of length 2, the slopes of the angled lake beds along the west and east shores of the lake (unitless).