new algorithm for id generation using parametrisation

[gyounes]

the j (number of jumps) parameter allows a more efficient behaviour.

• increasing j to a certain point (relatively to the number of ids generated) gives the optimal behaviour
• j should be at least 2 (maybe can be fixed, i will check)

[CBaquero]

This is a big modification, so maybe we should have more than one algorithm in the code. I will check with you how this one works first.

[gyounes]

I can be there when you want to check it if you prefer. I dont know if having two or more ... is better and how but there is definitely room for improvements.