jsmodbus CLI requires Commander

[mainstreetmark]

I installed jsmodbus globally, and attempted to run:

$ npm install jsmodbus -g 

added 4 packages, and audited 5 packages in 816ms

found 0 vulnerabilities
$ jsmodbus --help         
node:internal/modules/cjs/loader:927
  throw err;
  ^

Error: Cannot find module 'commander'

After globally installing commander, everything works.

[stefanpoeter]

@mainstreetmark Sorry for the late reply. I am always happy about pull requests.