[Clas12_verystrange] proposal update

[Lei Guo]

I updated sum.tex, Xisect.tex and beam.tex and added a few figures.

The Xisect.tex is bascially from the summary from Oh, Nakayama, and  
Helmut. I rewrote it so that it fits more with our proposal. I did not  
include anything yet from Winston's Xi prediction.

Can Derek, Michael and Johann please check the beam time section  
(prior to the summary). I have a summary of expected total number of  
Omega, Xi  and XI(1820). For omega, I basically got the numbers form  
the updated version of Derek's estimation. FOr Xi and Xi(1820) it's  
back-of-the-envelope calculation. Maybe Michael and Johann can check  
whether they are correct?

Again, I have a local verison of refences.tex that all the reference  
is working. But I think I need further double checking and will commit  
it once that is done.


Thanks a lot and cheers!

Lei