Using default style raises warnings about non style parameters

[jenshnielsen]

For instance:

import matplotlib
import matplotlib.pyplot as plt

matplotlib.style.use('default')
plt.plot(range(10))
plt.show()

raises

/usr/local/lib/python3.5/site-packages/matplotlib/style/core.py:52: UserWarning: Style includes a parameter, 'webagg.port_retries', that is not related to style.  Ignoring
  "style.  Ignoring".format(key))
/usr/local/lib/python3.5/site-packages/matplotlib/style/core.py:52: UserWarning: Style includes a parameter, 'datapath', that is not related to style.  Ignoring
  "style.  Ignoring".format(key))
/usr/local/lib/python3.5/site-packages/matplotlib/style/core.py:52: UserWarning: Style includes a parameter, 'figure.max_open_warning', that is not related to style.  Ignoring
  "style.  Ignoring".format(key))
/usr/local/lib/python3.5/site-packages/matplotlib/style/core.py:52: UserWarning: Style includes a parameter, 'timezone', that is not related to style.  Ignoring
  "style.  Ignoring".format(key))
/usr/local/lib/python3.5/site-packages/matplotlib/style/core.py:52: UserWarning: Style includes a parameter, 'backend.qt4', that is not related to style.  Ignoring
  "style.  Ignoring".format(key))
/usr/local/lib/python3.5/site-packages/matplotlib/style/core.py:52: UserWarning: Style includes a parameter, 'toolbar', that is not related to style.  Ignoring
  "style.  Ignoring".format(key))
/usr/local/lib/python3.5/site-packages/matplotlib/style/core.py:52: UserWarning: Style includes a parameter, 'savefig.directory', that is not related to style.  Ignoring
  "style.  Ignoring".format(key))
/usr/local/lib/python3.5/site-packages/matplotlib/style/core.py:52: UserWarning: Style includes a parameter, 'tk.window_focus', that is not related to style.  Ignoring
  "style.  Ignoring".format(key))
/usr/local/lib/python3.5/site-packages/matplotlib/style/core.py:52: UserWarning: Style includes a parameter, 'backend_fallback', that is not related to style.  Ignoring
  "style.  Ignoring".format(key))
/usr/local/lib/python3.5/site-packages/matplotlib/style/core.py:52: UserWarning: Style includes a parameter, 'webagg.open_in_browser', that is not related to style.  Ignoring
  "style.  Ignoring".format(key))
/usr/local/lib/python3.5/site-packages/matplotlib/style/core.py:52: UserWarning: Style includes a parameter, 'backend', that is not related to style.  Ignoring
  "style.  Ignoring".format(key))
/usr/local/lib/python3.5/site-packages/matplotlib/style/core.py:52: UserWarning: Style includes a parameter, 'interactive', that is not related to style.  Ignoring
  "style.  Ignoring".format(key))
/usr/local/lib/python3.5/site-packages/matplotlib/style/core.py:52: UserWarning: Style includes a parameter, 'webagg.port', that is not related to style.  Ignoring

[jenshnielsen]

This happens every time the test suite runs a test with the default style rather than the classic style after the merge of #5440

[mdboom]

I think this is due to the 11th hour addition of d9d1671 in #5440. Obviously that will have to be done differently -- probably to ignore, but not warn about, blacklisted parameters.

[efiring]

But ordinarily one would want the warning, so maybe a warn=True kwarg is needed, that can be set to False in d9d1671.

[jenshnielsen]

@efiring I agree. I think it would be ok to add a warn kwarg to _apply_style and pass it on to _remove_blacklisted_style_params which defaults to True and just set this to False when the default style is used.

[mdboom]

Yes -- I am only suggesting suppressing the warning when default is applied, which by necessity must have blacklisted parameters in it that should be ignored when using it as a style.

[jenshnielsen]

Cool Im happy to do a PR with that now

[mdboom]

Sorry -- didn't see your comment before I just made a PR (#5778). We can do that, or use a kwarg to disable warnings, as you suggest. I don't really have strong feelings either way.

[jenshnielsen]

Neither do I but I guess #5778 requires slightly less modification so I will merge that when travis passes and we are sure it works