GitLab

* add linearity test for istft
* one test needs to be relaxed from atol=1e-6 to atol=1e-5

* pitch detection validation.
* make torchscriptable.

* Fixed create_fb_matrix filter bank behavior for fmin/fmax
* add better test for f_min close to f_max
* added one more test for f_min > f_max
* adding one more test

* TimeStretch and Masking
* Doc stuff and naming

* compute deltas.
* multichannel, and random test.
* documentation.
* feedback. changing name of window to win_length.
* passing padding mode.

- Apply __future__ imports uniformly (future division is the biggy, but absolute
  imports mattered too)
- Hotfix use of tempfile.TemporaryDirectory using a BC library (DO NOT
  add this library as a dependency to torchaudio; it's only for testing)
- Replace math.gcd with fractions.gcd
- Fix a weird pytest collection bug involving parametrized tests
- Turn on Python 2 and Python 3.7 in Travis.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>

This makes it easier to test against an installed wheel, as the
torchaudio folder is no longer preferentially picked up when
you run a test module.

I had to move all tests in subfolders into the top level test
directory to make this work, since you can't access .. modules
without mucking around with sys.path (which I don't want to do.)

NB: this BREAKS the syntax where you can run a test by
saying `python -m test.test`.  Instead, do `python test/test.py`
or use the pytest runner.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>