Drop inherits, buffer-alloc dependencies

[feross]

Buffer.alloc and Buffer.from were added in Node 6. inherits is not needed if we use a class.

This change only drops support for Node 4 and lower, which no one should be running at this point. Especially since Node 6 is already EOL and Node 8 is about to be EOL in December 2019. :)

I also removed package-lock.json which is not useful in packages since it doesn't get published to npm. It's existence only ensures that package authors get outdated deps that the users are not going to get.

This is not a breaking change since the exposed interface is still the same, i.e.

var stream = mp4.decode()

and

var stream = mp4.encode()

I know this is a lot of code to review. The only transformations I made were:

• Remove inherits, buffer-alloc dep.
• Use an ES class
• Convert all self to this
• Remove all lines with var self = this
• Convert all anonymous functions to fat arrow syntax.

For: brave/brave-browser#5490

[feross]

3.1.0