small changes
TST: linalg.qz test fails for complex64, so lower test tolerance.

Appears to be an ATLAS regression (3.8 is OK, 3.10 is not).  Closes gh-2842.
enhanced signal tutorial
further signal tutorial enhancements
Fixed integer division in indices.
added detrend and spectral estimation
Fixed integer division in indices.
Included a call to set_iprint in TestODR.test_explicit
Fixed typo
Merge pull request #2910 from rgommers/issue-2842-qz

TST: linalg: qz test fails for complex64, so lower test tolerance.
TST: fftpack: remove check of successful overwrite

The overwrite may not happen if f2py decides to make copies e.g. due to
aligment. The purpose of the test is to check only that no spurious
overwrites occur.
Merge pull request #2941 from pv/fft-no-overwrite-assert

TST: fftpack: remove check of successful overwrite
Merge pull request #2924 from FabricioS/future_division_odr

BUG: odr: fixed integer division in indices
Merge pull request #2925 from ClemensFMN/signal_tut

DOC: Enhance signal tutorial
TST: fix spurious test failure in linalg.  Closes gh-2945.
TST: fix spurious failure in signal.savgol_filter test.  Closes gh-2947.
Merge pull request #2948 from rgommers/macports-failures

Fix two MacPorts failures