Resubmission

This is a resubmission. In this version I have

added the macos recipe 'fftw-s' to 'SystemRequirements'
rewrote the configure script to use pkg-config in order to test for fftw library with single precision support.

R CMD check results

0 errors | 0 warnings | 2 notes

CRAN incoming feasability
- New submission - Package was archived on CRAN
- Note: "Possibly misspelled words in DESCRIPTION: Broek (17:32) Lukas (16:57)."
  - Remark: I double-checked the spelling and it is correct.
- X-CRAN-Comment: Archived on 2024-07-01 as issues were not corrected in time.
- Incorrect 'SystemRequirements' (needs single-precision 'fftw' and does not test for it).
checking for future file timestamps
- unable to verify current time
  - Remark: apparently the web service in use is not reachable, the problem seems not to be on my end.