0.4.0

• Removed "built-in" backend support (providing strings for backend config)
  • Removed backends and registerBackend
  • This means you must now import the backends you would like to use with configure
• All backends are now exported
• The Backend and BackendConfig types are now exported
• MirrorFile is now exported
• OverlayFile is now exported
• FileFlag changes:
  • Renamed FromString to Get
  • Renamed NumberToString to StringOf
  • Added NumberOf
  • Renamed flagStr to _flag
  • Renamed validFlagStrs to validStrings
  • Changed private fields to protected
  • Made constructor protected, since it should never be called directly (use Get instead)
• Fixed encode and decode
• Added error handling for buffers passed to the Inode constructor that are too small
• Added Inode.birthtimeMs
• Removed Inode.sizeof
• Added Offset.end (for inodes)
• Added StatsLike (implemented by StatsCommon, Stats, BigIntStats, and Inode)
• Updated stats constructor to take StatsLike instead of lots of arguments
• Deprecated Stats.clone and BigIntStats.clone (use new Stats(o) instead of Stats.clone(o))
• Fixed the AsyncMirror validator for the sync option
• Changed many constants to use hex (0x) instead of octal (0o), for clarity
• Changed Mutex to a named export
• Renamed PreloadFile type parameter from T to FS
• Renamed LockedFS type parameter from T to FS
• Removed toPromise since it was unused
• Made setImmediate and mkdirpSync hidden
• Changed many internal imports to be type-only
• Marked some classes as internal