Use the newly-minted option generator script from dxcommon.

Instead of maintaining the relation between long options and help text
dircetly in C code, let's use this new script to generate C code from
a simple description file.

This ditches support for translated option names.  I'm a bit unsure
about the practical use of this functionality as I do not personally
use it and locale-specific interpretation of command-line arguments
just seems like it would cause more problems than it would solve.