FFTW v1.4.6

Diff since v1.4.5

Closed issues:

• Migrate to travis-ci.com (#166)
• Darwin ARM: libfftw3 not defined (#187)
• Unable to install latest version of FFTW on Julia 1.6 (#206)
• Problem with FFTW=1.4.3 ignoring DEPOT_PATH variable at runtime (#208)
• Latest FFTW release causes portability issues (#210)
• Support applying plans by column? (Or is it really 300x slower??) (#216)
• fft(x,dim) fails on Julia-1.7.0-rc1 (#220)
• First call to plan_rfft trashes the input (#226)

Merged pull requests:

• allow MKL 2022 (#228) (@KristofferC)
• Improve inferrability of dims_howmany (#231) (@timholy)