v2.0.0

This release modernizes fontkit to drop Node-specific dependencies so it can more easily be used in the browser.

• Usages of Buffer have been replaced with Uint8Array/TextEncoder/TextDecoder
• Encoding subsets is now no longer streaming. subset.encodeStream() has been replaced with subset.encode() which returns a Uint8Array.
• Optional dependency on iconv-lite has been dropped in favor of TextDecoder.
• There is now a separate browser build, which excludes the fs dependencies. This means there is no open or openSync method in browser environments.
• open now returns a Promise rather than accepting a callback.