Update to Seminar #2 and commment on seminar lecture on 22.02

Dear all,

in exercise 2 of Seminar #2 I have updated "Jenny's utility" to match my seminar today (22/02).

Also: for those in class today, in exercise 1 the production functions x=2l and y=3l were indeed the correct ones: changing them to x=(1/2)l and y=(1/3)l  was a mistake I made in class.

Jacopo