v0.0.1-rc7: build system fixes for std::filesystem on specific compilers

some compilers with early c++17 support put std::filesystem in an
experimental library/include dir. This conditions that.

Tested with gcc and clang on ata and chinook

Rel testing

If this doesn't work I'll just change the condition the cibuildwheel pipeline run on

v0.0.1-rc1

Mostly checking that "creating a release" from a tag is what triggers "published" event in github actions

0.0.1-rc0

This is the first release candidate for a new narrowband doppler-drifting ET search pipeline. The rough approach is:

Flagging

Use bitmasks to flag up to 8 RF conditions. Currently:

• magnitude
• filter rolloff
• spectral kurtosis

Noise estimation

Use unflagged spectra to estimate noise levels

Dedrift integration

Use linearly-rounded paths through spectrum to integrate doppler drift. Flag values along each drift are also collected

Hit finding

Use connected components or local maxima to identify hits in dedrifted spectrum

Event finding

Use a distance-based formula to match hits across scans to form events

Other implementation details of interest

ndarrays (bland)

deferred execution with memoization