When output is too big in scr.interactive there should be more options than just "Yes" or "No".

I'm proposing the following:

• p : use scr.pager (less, more, ..)
• 10 : any numeric argument will assume that it must flush only the first 10 lines and drop the rest.

We can add r_cons_head() and r_cons_tail() functions to chop the non-flushed buffer.