[Draft] add single-argument kernel evaluator

[lu1and10]

To address issue #528, added a single-argument kernel evaluator using current polynomial coefficients.

@ahbarnett In case you want to test the coefficients sooner. I tested by replacing evaluate_kernel((FLT)z[n], opts); with evaluate_kernel_horner((FLT)z[n], opts); in functions onedim_fseries_kernel and onedim_nuft_kernel, make test still passes.

This may be merged after 2.3 release.