Do not clamp triangle mutation ?

[Cerdic]

I saw that triangles are clamped when mutating, to stay in the bounds
https://github.com/Tw1ddle/geometrize-haxe/blob/master/geometrize/shape/Triangle.hx#L38

whereas they are not clamped in the constructor (corners 2 and 3 can be out of the bounds).

As a matter of fact it seems better to not clamp the corners while mutating, allowing to get partly out of the bound triangles, whereas this is now only possible to with initial random triangles