Implements the N-Power Fourier Deconvolution (NPFD) method for
nonparametric density deconvolution when observations are available from
a convolving distribution and the corresponding convolved distribution,
but no direct observations are available from the target distribution.
Functions are provided for deconvolution, construction of samples from
replicated mixed measurements, and spline-based density estimation.
The methodology is described in Anarat, Krutmann and Schwender (2026)