[python-control-developers] [python-control/python-control] ce3a23: add capability to switch to legacy defaults (#424)

[sawyerbfuller <no...@gi...>]

  Branch: refs/heads/master
  Home:   https://github.com/python-control/python-control
  Commit: ce3a231e8c93d1f283e85c3cb95ec03243c762c3
      https://github.com/python-control/python-control/commit/ce3a231e8c93d1f283e85c3cb95ec03243c762c3
  Author: sawyerbfuller <587...@us...>
  Date:   2020-07-11 (Sat, 11 Jul 2020)

  Changed paths:
    M control/config.py
    M control/statesp.py
    M control/tests/config_test.py
    M control/xferfcn.py
    M doc/conventions.rst

  Log Message:
  -----------
  add capability to switch to legacy defaults (#424)

* add capability to switch to legacy defaults with config.use_legacy_defaults(version)

* reverted to using matrix as default in statesp to pass tests

* added documentation to statesp, xferfcn, and conventions.rst describing new config parameters default_dt and remove_useless_states