Pffra

The first formal release extends the previous Fourier transform-based PFFRA to enabling wavelet transform-based PFFRA.

Update for grand a DoI

1. Open more customised interfaces to give users more freedom to use blocks in the PF-FRA algorithm.

> - Now each built-in method of PermFeatureFreqRespoAnalysis object is callable to allow users to input customised parameters.
> - Add 'shuffle' mode for feature permutation.

2. Correct some minor typos in the code to improve its readability.

Fix some minor typos and bugs in the first version source code.

First major release.