TRB formatting; CECP sponsor logos & beamer theme tweak

new file:   trb.tex
- WIP formatting for a TRB paper submission, based on
  http://ite.ce.gatech.edu/?p=681

modified:   beamerthemeCECP.sty
- Change a \setbeamertemplate to a \defbeamertemplate, so the CECP frame
  background can be turned on/off in mid-presentation

new file:   cecp/logo-afd.png
new file:   cecp/logo-ef.gif
new file:   cecp/logo-eni.svg
new file:   cecp/logo-icf.svg
new file:   cecp/logo-shell.svg
- Logos of CECP sponsors for convenience; copyright lies with respective
  owners