Creates stopping power data tables from libamtrack and exports
them in TRiP98 compatible format. For the DEDX format, see M. Kr\"amer's
TRiP98 documentation:
http://bio.gsi.de/DOCS/TRiP98BEAM/DOCS/trip98fmtdedx.html. N.B. check
the resulting data carefully for NAs, as not all stopping power data sources
might cover the energy grid requested.