Added qden() for quantile density estimation using QOR-based and density-based methods.
Added qor() for computing quantile optimality ratios using the generalized lambda distribution, lognormal, normal, exponential, and user-supplied quantile functions.
Added qrcov() for covariance matrix estimation for ratios of linear combinations of quantile estimators.
Added rcv.test() for one- and two-sample inference for robust coefficients of variation based on the MAD or IQR.
Extended qcov() to use the new quantile density estimation framework, including flexible distributional choices for QOR-based estimation.
Extended qineq() to support additional quantile-based inequality measures and user-specified measures.
Updated q.test() to improve quantile-based inference and argument handling.
Improved input validation, documentation, and error and warning messages throughout the package.
Expanded the automated test suite to cover the new and updated functions.
NEWS.md file to track changes to the package.