Random Covariance Values

An extension to CovXYs.py. In this IPynb, it was aimed to find the
neighborhood of a random coordinate on the grid and its corresponding
CovXX or CovXY value by using the formula z = z1 + ((z3+z2-2*z1)/
2*L)*x + (z3-z2/ 2*h)*y. This is a prototype, so as it is improved,
github will be updated.