As a developer I want to replace N4MF files by package JSON files

[mor-n4]

Instead of defining dependencies etc. in the manifest, we need to use package.json. There must be no redundancies!

Some information may not be found in the package.json by default. We need to decide whether we want a separate file (in json format, similar to typescript) or a section in the package json (similar to linters) containing that information. We would prefer using only package.json -- investigate why TypeScript uses a different file.

We need to be able to read all information from package.json that are important for n4js.

Acceptance Criteria

• Dependencies, Name, Version etc. are read from package.json
  • this includes supporting semver syntax as defined in package json
• Missing information is available either in package.json or n4js.json depending on decision above
• n4mf related plugins are removed (to be clarified how we do that)
• spec updated
• When no type information is additionally provided, the library manager must NOT change the downloaded NPMs at all. At the moment, the library manager automatically adds the manifest and may perform other changes. This must not happen anymore.