* master: (22 commits)
  Welcome @singingknight as a collaborator
  Fix a typo
  Better windows support (#104)
  Moving format check from diagnose to prepare (#99)
  Ensure that .git folder is also ignored
  Build browser list
  Add type assertion for enzyme wrappers
  Upgrade packages and run Prettier
  Declare missing files
  Progress on `fulfills()` spec
  Add `subtract()` and `union()`
  Some alfa compatibility tests (#89)
  Implement `isExposed()` and refactor `isVisible()`
  Refactor `Option` type and associated functions
  Initial documentation of ACT types
  Update TypeScript
  Fixes #102: Make `Value` type default to `unknown`
  Better tracking of `Project` version
  Cache working directory and internalise properties
  Minor refactoring of `Project`
  ...