remove dependency on github.com/hpcloud/tail

[mohammed90]

Updates #622 and adds Windows support as positive side-effect

[mohammed90]

Okay, I'm at loss now. The failures recur despite the code is almost exactly as it were, except for the streaming part and a few additional OS-specific files. Different Go versions have different results, though Go 1.12.x and Go tip have matching results. Those particular tests don't seem to be run for other PRs and master, which is odd given that the test suit doesn't seem to have changed lately (unless I'm mis-seeing).

Successfully removing github.com/hpcloud/tail makes the this package usable on Dragonfly and Illumos. I've addressed the limitation for Plan9. Nacl is a different story.

[blgm]

#667 has replaced the github.com/hpcloud/tail package with another one. I'm wondering whether it's worth keeping this PR, or whether #667 has solved the underlying problem.

[mohammed90]

I guess it isn't needed anymore.