[INTERNAL] package.json: Define files to publish

[RandomByte]

Package sizes (tested by executing npm pack):

Before
npm notice package size: 29.0 kB
npm notice unpacked size: 107.2 kB

After
npm notice package size: 17.8 kB
npm notice unpacked size: 64.2 kB

=> Reduction of ~40%

New package content:

❯ tree                                                       
.
├── CHANGELOG.md
├── CONTRIBUTING.md
├── LICENSE.txt
├── NOTICE.txt
├── README.md
├── index.js
├── jsdoc.json
├── lib
│   ├── AbstractReader.js
│   ├── AbstractReaderWriter.js
│   ├── DuplexCollection.js
│   ├── ReaderCollection.js
│   ├── ReaderCollectionPrioritized.js
│   ├── Resource.js
│   ├── adapters
│   │   ├── AbstractAdapter.js
│   │   ├── FileSystem.js
│   │   └── Memory.js
│   ├── fsInterface.js
│   ├── resourceFactory.js
│   └── tracing
│       ├── Trace.js
│       └── traceSummary.js
└── package.json

[coveralls]

Pull Request Test Coverage Report for Build 89

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 58.719%

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Totals
Change from base Build 79:	0.0%
Covered Lines:	316
Relevant Lines:	513

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💛 - Coveralls