Add stream loaders, revise JSON formats.

[jheer]

• Breaking: Drop custom Arquero JSON format with embedded schema. It provides little if any additional value (as the schema does not include type information), and I don't have any evidence that people use it.
• Add support to load data from input readable streams.
• Add full streaming readers for CSV, fixed width, and NDJSON formats.
• Add support for gzip and deflate decompression of input streams.
• Add fromArrowStream, fromCSVStream, fromFixedStream, and fromJSONStream methods for async stream parsing.
• Expand fromJSON and toJSON to support a JSON type property, for control over row-oriented, column-oriented, and newline-delimited (NDJSON) formats.
• Update build, including package.json use of the browser property, for more targeted node/web separation.
• Update test cases to reflect changes.