dunyuliu/plambda: Initial release of grinv & plambda: Geophysical analysis toolkit with GUI applications

Geophysical analysis toolkit with GUI applications: grinv: Von Kármán covariance parameter inversion for bathymetry/topographic profile analysis (H2, k0, nu parameter estimation). Must be run before plambda. For full details, see https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/JB093iB11p13589. plambda: Power spectral density analysis using "emperical pre-whitening" to detect and quantify periodicities that are embedded within an otherwise aperiodic random function with parameters estimated with grinv. Emperical prewhitening is accomplished by first computing the autocovariance function, then zeroing out the central, decaying portion, and finally computing the Fourier transform to form a spectral-domain function that has zero mean. Periodicities are evident as discrete peaks in the spectral-domain function that rise well above the "typical" random variability, which is defined by sigma values. For full details see https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020GC009261, and/or download pdf poster at https://utexas.box.com/s/9kvu990qav591ayzcjaht14w5zybjfrk.