RF-model: Added complexity parameter to Tree object. Not really used yet.
RF-model: some comments cleaning + the return of the stack!
RF-model: set votes in every nodes.
RF-model: going to copy samples inside each nodes

Will do something memory efficient in our next move.
Merge branches 'master' and 'master' of https://github.com/datalayer/model
RF-model: almost ready for the stack
RF-model: stack is now live

But memory consumption is also inefficient