Design Doc: Initial CLI program

Looking for something like this:

symcurve [options] <input.fasta.gz> <output.bigWig>

OPTIONS:

   --matrices <symcurve_mat.yml>  custom roll/twist matrices
   --curve-step <int>             default 15
   --curve-scale <0-1 float>      default 0.33335
   --curve-step-one <int>         default 6
   --curve-step-two <int>         default 4
   --symcurve-win <int>           default 101
   --symcurve-step <int>          default 1
   --min-linker-size <int>        default 30
   -v,--verbose                   more detailed output

• Probably use Clap.