0.18.0

• Implemented the watch API/features (#6)
• Permissions are now handled in the emulation layer, not by individual backends
  • Removed redundant permissions checks in backends
  • Credentials are no longer passed to FileSystem methods
    • This change greatly simplifies the FileSystem API, making it easier to write backends
    • It is also a major breaking change for the internal API
  • Backends that need them can import credentials
  • Simplified credentials handling to use the exported credentials object
  • Credentials were already managed globally
• Corrected the syscall in some ErrnoError.With calls
• _openSync now truncates the file instead of deleting and recreating it (when the flag is truncating)
• Clarified link parameter names
• PortFile.stat now returns a Stats instance
• link correctly throws an error when attempting to make a cross "device"/backend link
• Simplified directory listing encoding/decoding
• Added deadlock avoidance to Mutexed
• Fixed Dir._entries initialization
• Added missing early return in mkdir