stream: Throw on 'error' if listeners removed

In this situation:

    writable.on('error', handler);
    readable.pipe(writable);
    writable.removeListener('error', handler);
    writable.emit('error', new Error('boom'));

there is actually no error handler, but it doesn't throw, because of the
fix for stream.once('error', handler), in 23d92ec.

Note that simply reverting that change is not valid either, because
otherwise this will emit twice, being handled the first time, and then
throwing the second:

    writable.once('error', handler);
    readable.pipe(writable);
    writable.emit('error', new Error('boom'));

Fix this with a horrible hack to make the stream pipe onerror handler
added before any other userland handlers, so that our handler is not
affected by adding or removing any userland handlers.

Closes #6007.
Merge remote-tracking branch 'ry/v0.10'
http: removed headers stay removed

This allows automatically-inserted headers to be removed permanently by
calling OutgoingMessage.removeHeader() on them, as if they were normal
headers.
fixes #6031 spelling errors

explictly => explicitly
accesss => access
througput => throughput
epxression => expression
communiction => communication
becuase => because
repersent => represent
condonitions => conditions
decompresion => decompression
intentially => intentionally
eventes => events
listning => listening
resicved => received
becuase => because
fundimental => fundamental
colapse => collapse
privlages => privileges
sufficently => sufficiently
hapepns => happens
expliclitly => explicitly
thier => their
shold => should
events: have events module exports EventEmitter

This change is 100% backwards compatible.

This change will make using `EventEmitter` slightly simpler / nicer and
adheres to the best practice set forth by substack.

```js
var EventEmitter = require("events")

var emitter = new EventEmitter()
```

The only difference is that we now have to set `EventEmitter` as a
property of `EventEmitter` for backwards compatibility like we do with
[`Stream`][1]

We have also set the `usingDomains` property on the `EventEmitter`
constructor itself because that aligns with it's current usage of
`require("events").usingDomains = true`

There are other internals that would benefit from this change as well
like `StringDecoder`
test: Remove unnecessary assertion

It only fails once in about 1000 times, but that's too many.
It's timing dependent, and the main behavior is covered by the other
assertions in the test anyway.
net: family option in net.connect

`dns.lookup` defaults to selecting IPv4 record even if IPv6 is available
for the desired zone. Generally, this approach works, but if IPv4
address is unavailable - there'll be no other way to opt-out and connect using
IPv6 address than calling `dns.lookup` and passing it to `.connect()`
directly.

This commit adds `family` option to `net.connect` method to figure out
this issue.
util: isObject should always return boolean

Fix small bug where isObject would return the original object instead of
true.