light, featureful and explicit option parsing library

 The author of the library gives this rationale: the other option parsing
 libraries are one of too loosey goosey (not explicit), too big/too many deps,
 or ill specified.
 .
 This library is a dependency for sshpk, a library to parse, convert,
 fingerprint and use SSH keys (both public and private) in pure nodejs.
 .
 Node.js is an event-based server-side JavaScript engine.