Works in QtConsole if you initialize the qt event loop with:

from PyQt5.QtWebEngineWidgets import QWebEngineView
%gui qt

QWebEngineView import must precede the %gui qt command.

Added orca server process management tests

 - Save/load settings from ~/.plotly/.orca file
 - More validation
 - write image
 - add image options (format, size, scale)

Lets save some complexity and not support using an external orca
server for now.

The old approach required OS-specific process management and it still
didn't kill the child process for orca installed with npm.  Now
all of the OS-specifics are in psutil.

psutil is an optional import that is check when the server is first
requested.

We could leave the plotly.io._show module in place, so people could
experiment with the image backend concept.

It emits some errors when children are killed, but these are harmless

This way program exist won't wait for it to complete

…Mathjax CDN

 - Add topojson files to `plotly/package_data`
 - Add new config settings for plotly.js bundle (use local by default), topojson, mathjax, and mapbox access token
 - Add image tests for `topojson` images and mathjax images
 - Remove saving of orca config to ~/.plotly. Need more a more wholistic settings solution that handles environments
 - Shutdown server when setting config parameters that won't be active until server restarts (e.g. plotlyjs bundle)
 - Make default timeout None. So shutting down the server due to inactivity is now opt-in.

details in error message.

…2 downgrade)

Should keep Python version constrained and be a bit faster.

 - Remove text (Except for latex)
 - Fix width/height

 - plotlyjs is now a constant
 - topojson now points to CDN by default

 So now, default settings aren't specific to a particular environment.
 And if someone changes a setting, the change makes sense across
 environments.

This greatly reduces the number of dependencies needed.

Try downloading miniconda 3 for Python 2 workflow

…ical

to bypass figure dict validation.

Also improve presentation of orca error messages and added a special
check for EPS failures that might be due to the needed poppler
dependency

… fails to communicate

with the orca server process.

Needed for EPS tests

On windows, this avoids Popen being unable to find the orca executable
when it is on the environment path. [ci skip]

[skip ci]

If orca returns a 525: 'plotly.js error', and the figure contains
at least one mapbox trace, and not mapbox_access_token is configured,
then include a error message explaining what to do.