Removed the 2 from CH2 in the atom list in the element determining function.
This is in response to Vitaly Vostrikov's <vvostri att gmail dott com> message at Message-id:
<AANLkTimYA4H7=WbMwzgpxaTJ6_nArKu=ed9VNdXCSuDB@...>,
https://mail.gna.org/public/relax-users/2010-12/msg00013.html.
