Fix Plotly Flicker on Quick Updates

[da-h]

Description

Quick redraws of Plots tends to flickering (see example below). This PR fixes this by using the optimized Plotly.react instead of Plotly.newPlot for each redraw.

Motivation and Context

The bug has been spotted in #903. Edit: While this fix does improve the flickering, it may still occur. I suggest to still apply this more stable visualization and check alternative ideas in a future-PR.

How Has This Been Tested?

As suggested in #903, the flickering is best visible for heatmap plots. The following code-snippet reproduces the error.

def plot_surface_append_many(viz, env, withnames=False):
    win = plot_surface_basic(viz, env, withnames)
    viz.heatmap(
        X=np.outer(np.arange(6, 9), np.arange(1, 11)),
        win=win,
        update="appendRow",
        opts=dict(rownames=["y6", "y7", "y8"] if withnames else None),
        env=env,
    )
    import time

    for i in range(100):
        viz.heatmap(
            X=np.outer(np.arange(1, 9), np.arange(11, 14)),
            win=win,
            update="appendColumn",
            opts=dict(
                columnnames=["c1", "c2", "c3"] if withnames else None,
                colormap="Rainbow",
            ),
            env=env,
        )
        time.sleep(0.1)

Without this Fix	With this Fix

Types of changes

• [x] 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:

• [x] I adapted the version number under py/visdom/VERSION according to Semantic Versioning 0.2.3 -> 0.2.4
• [ ] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.

[da-h]

Update: As mentioned in #904, flickering may still occur occasionally, but less frequently. Possibly https://github.com/plotly/react-plotly.js is a more robust solution?

I still suggest to merge this in, as it should provide a smoother although not perfect experience, yet.