New more efficient (and ugly) way of creating .self$variables

[mikula]

R is not suitable for manipulation of chains of pointers thus it is not convenient for recursive programing of tree structures. This is a new lesson for us. To keep the package writen entirely in R we were forced to copy lists many times. It works for small examples but with big data sets (10-20 000 columns) this method consumes lot of cpu-time.

An alternative, although less elegant, method will be proposed in this issue