v0.7.0

Changed

• [BREAKING] Replaced files getter/setter on <playground-project> and
  <playground-ide> with config getter/setter. This property has the same
  type as the JSON config, and can be used to save/restore the state of all
  files and other configuration.

Fixed

• TypeScript errors of the form Property '...' does not exist on type and
  Cannot find name '...' are now suppressed (temporarily until d.ts files
  are fetched).