fixed issue where large image would render in different env

[Aryanamish]

Updated the backend to send the environment ID with the render information.

Updated the Front End to ignore the incoming window when it is not in the currently selected environment

Motivation and Context

issue #80

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Code refactor or cleanup (changes to existing code for improved readability or performance)

Checklist:

• I adapted the version number under py/visdom/VERSION according to Semantic Versioning
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[JackUrb]

A nice simple fix to a longstanding problem. Thanks for taking this on @Aryanamish!

[JackUrb]

Hm I'm unsure why the tests are failing here, it may be a good idea to rebase then regen the minified frontend.

[da-h]

Great bugfix!

As a side-note:

• In the "Files changed"-Tab above, Github shows the Linter-Error positions. (I just found out that this feature exists 😅 ).
• The failing Visual Regression Test leave me a bit puzzled. I would also guess that rebasing should solve these. Otherwise there are possibly some unexpected side-effects? I'll look into this if it's failing again after rebase.

[Aryanamish]

I fixed the linting error

[da-h]

The failing of the functional test seems legitimate to me:
This PR in its current form does not work for forked environments.

Reason is that the state of each window does not yet adapt to the new eid when forking. (See https://github.com/fossasia/visdom/blob/master/py/visdom/server/handlers/web_handlers.py#L472).
I.e. the windows are stored under the forked eid, however the windows (local) state contain the eid the windows belong as well, which has not been adapted, yet.

The Python Linter-Error can be fixed easily.

The visual regression tests: see update below.

Regarding the other failing tests:

1. What I do not understand, yet, is why the visual regression tests are failing. The error says that the visual test-image dimensions do not match, which i cannot confirm from looking shortly into it. I'll look into it later/tomorrow in more detail. (For update, see below).
2. The Javascript Linter can be ignored for now. I have a solution at hand, fixing all these errors, but need just a bit more time to finish the PR conscientiously.

Best,
da-h

[da-h]

Update:

I've checked the visual regression test, which is legitimately failing as well:

For instance the end-state for the test compare_plot_line_multiple looks like this:

but should contain this compare plot:

[JackUrb]

Moving to a change request based on @da-h's analysis.