Opt: Simplified preprocessing of options

Opt: Simplified preprocessing of options

Replaced OPT_TRAVERSE_SECTIONS by proper recursion.

oc->opts now contains struct opt_precomputed's directly instead
of pointers to them, so that we need not allocate each struct
separately (and leak memory).

Counting of each OPT_CL_BOOL option twice has been removed, I hope
it is not necessary any longer as the "no-" prefix does not need
its own entry.