[Yanl-develop] interface change

[Karsten A. <kar...@gm...>]

Hi all,

I have changed the interface of stepper functions. Now, one has manually
adjust the size of the internal containers. Therefore, every stepper
function has a function _adjust_size( x )_ . The reason is simple:
Checking the size during each step might be time consuming, think for
example of a  badly implemented lists or graph types.

Best regards,

Karsten