Add uncertainty outputs for ground displacment prediction equations in newmark.py

[kallstadt-usgs]

Also add other equations
Watson-Lamprey and Abrahamson 2006
Bray and Travasarou 2007
Ambraseys and Menu (1988)
Ia options from Rathje, Saygili papers (need term to convert to Ia)

Bray, J. D., and Travasarou, T. 2007. “Simplified procedure for estimating
earthquake-induced deviatoric slope displacements.” J. Geotech.
Geoenviron. Eng., 133_4_, 381–392.

Watson-Lamprey, J., and Abrahamson, N. 2006. “Selection of ground
motion time series and limits on scaling.” Soil Dyn. Earthquake Eng.,
26_5_, 477–482.