Pisces

* Add initial response reader module.
* Add `request.py` to top `pisces` namespace explicitly.

* Replace deprecated `._copy()` method on SQLAlchemy columns with `deepcopy`
* New contributor Brady Spears!

* Drop testing on Python 3.6, add 3.9 and 3.10
* Drop AppVeyor for testing on Windows, use GitHub Actions instead
* The unimplemented `stime` keyword in `pisces.request.get_stations` has been replaced
with `time_span`, which accepts time ranges as YYYYddd julian dates.
* Fixed typo in `pisces.request.get_stations` implementation of `nets` keyword.
* New handling of wildcards in `pisces.request.get_stations`
* Fixed typo in `pisces.request.get_stations` implementation of `channels` keyword.
* Fixed typo in `pisces.requests.wfdisc_rows_to_stream` 😳 Yikes!
* New contributor Samuel Chodur!
* Use GitHub Actions for wheels and releases to PyPI
* Add `asquery` option to `pisces.request.get_waveforms`

* Bump required SQLAlchemy version to add least 1.4
* Updated import locations of `sqlalchemy.ext.declarative.api` functions to `sqlalchemy.orm`
* Changed the `Column.copy()` method to `Column._copy()` in `pisces.schema.antelope.py`,
`pisces.schema.css3.py`, and `pisces.schema.kbcore.py`. This remove deprecation warnings.

* fix bug in `io.readwaveform.read_s3` where too many return values were expected. (Issue 46)
* `wftag` now parsed as a float instead of an integer in KB Core and CSS3 schemas
* `Wftag` primary keys are `tagname`, `tagid`, and `wfid` instead of just `tagid`

* Pisces no longer requires compiling and installing C extension modules.
* Remove `libconvert` C library, and replace it's only exposed function (`s3tos4`)
with a NumPy-only version.
* Remove `libecompression` C library, and move it to a separate "e1" package on PyPI.
It will be installed as an optional dependency by installing with `pip install pisces[e1]`.