lack of ppmtompeg from netpbm package disrupts VMD tutorials

There is no ppmtompeg in current netpbm binary rpm distribution at least for fedora due to legal issue(?). This is going to be very annoying for administrator to deploy workstation for computer lab for molecular simulation. REF: http://www.ks.uiuc.edu/Research/vmd/mailing_list/vmd-l/14091.html