`BezierConnector` overcompensates if its `length` is close to or less than its `curviness`

[Domiii]

Can you change the Bezier algorithm to use Straight instead once edge length gets close to or less than curviness? Maybe in form of some straightThreshold option?

Here are some examples of how Bezier gets really messy once edge length gets short.

In the first example, the two nodes have a distance of about 2 x curviness, second 1 x curviness, third .5 x curviness:

For reference: "Curved Connectors" in Google Slides straighten out when the connecting surfaces have a very low relative angle. That is also ok, but maybe harder to implement? (Also, it bugs out with non-rectangular shapes, where connectors come in at a too low angle.)

[sporritt]

this reminds me of this PR that seems pretty cool but for some reason never got merged

jsplumb/jsplumb#41

it's too late to merge that in now as the codebase is completely different, but perhaps the idea could be implemented in the current codebase.

[ignapas]

This behavior with bezier connections is also observed when anchors are at the same height:

and even

This appears to solve it: #1056