Allow to suspend and resume updating smoothly

[leleogere]

Overview: What does this pull request change?

Modification of update, suspend_updating and resume_updating functions of Mobjects to be able to suspend and resume updating smoothly instead of instantaneously.
Deletion of the attribute updating_suspended of Mobject.
Addition of the attributes updating_speed which represent the speed of the updater (0 for stopped, 1 for full speed, in between for intermediate speeds).
Addition of the attribute updating_variation which represent the acceleration of the updating (deceleration if negative).

Motivation and Explanation: Why and how do your changes improve the library?

When dealing with objects with updaters, I sometimes need to temporary suspend the animation to enhance a specific point for example. Until now, the only way was to use my_object.suspend_updating(), which interrupts the animation too abruptly. I wanted a way to better control this interruption.
With this PR, we are now able to do things like:

my_object.suspend_updating()
my_object.suspend_updating(run_time=3)
my_object.suspend_updating(recursive=False, run_time=3)
my_object.suspend_updating(run_time=5, rate_func=smooth)

And of course the same parameters are usable with resume_updating.

Smooth_updaters.mp4

Links to added or changed documentation pages

Small modifications to reflect the new parameters.
https://docs.manim.community/en/stable/reference/manim.mobject.mobject.Mobject.html?highlight=suspend_updating#manim.mobject.mobject.Mobject.suspend_updating
https://docs.manim.community/en/stable/reference/manim.mobject.mobject.Mobject.html?highlight=suspend_updating#manim.mobject.mobject.Mobject.resume_updating
https://docs.manim.community/en/stable/reference/manim.mobject.mobject.Mobject.html?highlight=suspend_updating#manim.mobject.mobject.Mobject.update

Further Information and Comments

I'm facing issues when the flag --disable_caching is not passed. It looks like the renderer doesn't make well the link between animations. I don't know how to fix this tho...

Smooth_updaters_caching_issue.mp4

EDITS

I'm not currently working on this PR as issues with frame number have not been resolved yet and are likely causing problems to my implementation (see #698).

Reviewer Checklist

• The PR title is descriptive enough for the changelog, and the PR is labeled correctly
• If applicable: newly added non-private functions and classes have a docstring including a short summary and a PARAMETERS section
• If applicable: newly added functions and classes are tested

[MrDiver]

Any updates on this ?

[leleogere]

Any updates on this ?

No sorry, I put this aside for now, it has too much issues (e.g. with the caching system). I might give it another attempt when we will have a cleaner architecture. You can close it for now, I won't have probably the time/motivation to work on it for the next few months.