why delete chamfer from options?

[itgoldman]

deleting properties from options prevents user from passing same options to several bodies.

[wilcooo]

I agree that this is weird. The reasoning might be that we don't want/need the chamfer property on the created body (and a body clones all the options properties). However, Body.create will always create a chamfer property anyway, set to null... This property doesn't seem to be used anywhere, it might be just there to make the linter happy.

To make this consistent, this PR should be merged or chamfer should be deleted from the "default" body options in Body.create.