commented and added python scripts relevant to terramechanics.
-TireCrossSection.py plots the 2-D cross section of a union of 2 toroids
-WongReece.py a class to re-create plots from Wong (1967)
-plot_WongReece.py creates the plots from Wong (1967)
- lateralEarthPressure.py creates useful plots for determining the lateral earth pressure strength of soil (i.e., bulldozing forces)
- shearTheory.py plots the shear strength according to Justin's PhD thesis
- literature_tests_BousCerruit.py re-create the plots for pressure in a semi-infinite medium via a surface load from Wong (2001)