* Create test Action

Copied from fsnotify and restricted to macOS

* fixes broken test on macOS 11.5.2

* Remove Travis CI and Code Cov

replace with GitHub Actions in #54

This PR adds comprehensive doc comments to all exported
constants, mostly derived from the Apple documentation
but with changes to make them directly relevant to this package's API.

It also uses C constants directly rather than relying on an implicit
association between `1<<iota` and the actual enum values.

It also unexports `GetStreamRefPaths`, `GetStreamRefDescription`
and `GetStreamRefDeviceID`  because none of them are usable
with this package's API because there is no way to get an
`FSEventStreamRef` value because it's hidden inside an unexported
field inside the `EventStream` struct.

Also unexport the `CFRunLoopRef` because it's similarly
not useful or usable.

Other than the above unexports, the API remains identical.

Unfortunately I am unable to get the tests to pass, which
makes me think that something is wrong somewhere, but
that applies to the original code too, not just the code with
these changes applied.

* Return an error if FSEventStreamStart fails

* Validate the 4096 path limit and error detection

* Add notes for #46 and #48 limitations of macOS

Co-authored-by: Martin Tournoij <martin@arp242.net>

Fixes #51

Also update gofmt, some outdated patterns.

==================
WARNING: DATA RACE
Write at 0x00c000394018 by goroutine 10:
  github.com/fsnotify/fsevents.TestIssue48()
      /Users/runner/work/fsevents/fsevents/fsevents_test.go:137 +0xcc6
  testing.tRunner()
      /Users/runner/hostedtoolcache/go/1.17.13/x64/src/testing/testing.go:1259 +0x22f
  testing.(*T).Run·dwrap·21()
      /Users/runner/hostedtoolcache/go/1.17.13/x64/src/testing/testing.go:1306 +0x47

Previous read at 0x00c000394018 by goroutine 12:
  github.com/fsnotify/fsevents.TestIssue48.func1()
      /Users/runner/work/fsevents/fsevents/fsevents_test.go:112 +0x1d2

Goroutine 10 (running) created at:
  testing.(*T).Run()
      /Users/runner/hostedtoolcache/go/1.17.13/x64/src/testing/testing.go:1306 +0x726
  testing.runTests.func1()
      /Users/runner/hostedtoolcache/go/1.17.13/x64/src/testing/testing.go:1598 +0x99
  testing.tRunner()
      /Users/runner/hostedtoolcache/go/1.17.13/x64/src/testing/testing.go:1259 +0x22f
  testing.runTests()
      /Users/runner/hostedtoolcache/go/1.17.13/x64/src/testing/testing.go:1596 +0x7ca
  testing.(*M).Run()
      /Users/runner/hostedtoolcache/go/1.17.13/x64/src/testing/testing.go:1504 +0x9d1
  main.main()
      _testmain.go:55 +0x22b

Goroutine 12 (finished) created at:
  github.com/fsnotify/fsevents.TestIssue48()
      /Users/runner/work/fsevents/fsevents/fsevents_test.go:107 +0x815
  testing.tRunner()
      /Users/runner/hostedtoolcache/go/1.17.13/x64/src/testing/testing.go:1259 +0x22f
  testing.(*T).Run·dwrap·21()
      /Users/runner/hostedtoolcache/go/1.17.13/x64/src/testing/testing.go:1306 +0x47
==================

Experience with fsnotify has shown this can be an issue, and the tests
here seem fast enough.

…ScheduleWithRunLoop (#62)