Support new third-party package schema

[na4zagin3]

The discussion is going on in the SATySFi-Slack.

It would be like this.

1. Directory hierarchy.
   1. Files related to a package are located under $LIBROOT/dist/packages/[<namespace>/]/<package-name>/<package-name>.<package-semver>/.
   2. Package description file (like Node.js’s package.json), which is also located there, indicates files to load.
2. Import
   1. @require: [<namespace>/]<package-name>[.<package-semver>]
3. Namespace
   1. For example, na4zagin3/grcnum.0.1.0

[na4zagin3]

We can switch the feature to keep backward compatibility.

• satyrographos 0.0.1 series keep the behavior
• satyrographos 0.0.2 series provide the new schema by default

Regardless of series, automatic install assumes the new package schema.

[na4zagin3]

We need to rethink about semvar. Allowing multiple versions of a library can break type safety.