Make bouncing the default for constraints

[jrapin]

Types of changes

• Docs change / refactoring / dependency upgrade
• 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 change)

Motivation and Context / Related issue

This is a follow-up of #684 making bouncing the default for bounding constraints. Hard clipping on the bounds can lead to very detrimental loss of diversity. Bouncing on the border can help avoid this in being closer to an actual constraint through resampling, while being much more efficient in large dimension
Closes #621

How Has This Been Tested (if it applies)

Checklist

• The documentation is up-to-date with the changes I made.
• I have read the CONTRIBUTING document and completed the CLA (see CLA).
• All tests passed, and additional code has been covered with new tests.

[teytaud]

Do I understand correctly that bouncing is tested once and then clipping is applied ?

[jrapin]

Do I understand correctly that bouncing is tested once and then clipping is applied ?

What do you mean tested once?
It "bounces" once on the border, and if it reaches the other border then it clips:
Eg: starting point 1, and bounds in [0, 10]:

• moving of -3 leads to 2
• moving of 1 leads to 2
• moving of 10 leads to 9 (bounces once on border)
• moving of -11 or lower leads to 10 (bounces once at 0, then clips at 10)