- build: moved from travisCI to GitHub Actions
 - docs: refurbish docs
 - tests: allow 2D Fourier mapping test to fail on macOS
   and Windows (don't know why it fails, probably unstable)
 - ref: replace np.complex256 with np.complex128 in
   _alg_int.py:integrate which does not break any tests but
   works on Windows which sometimes has not support for longdouble
 - ref: replace np.bool with bool due to numpy deprecation warnings