dgram: fix abort when getting `fd` of closed dgram

v8's `messages.js` file's `CallSiteGetMethodName` is running through all
object properties and getter to figure out method name of function that
appears in stack trace. This run-through will also read `fd` property of
`UDPWrap` instance's javascript object, making `UNWRAP()` fail.

As a simple alternative to the test case above, one could just keep
reference to the dgram handle and try accessing `handle.fd` after it has
been fully closed.

fix #6536
net: fix `new net.Socket` documentation

`Socket` no longer accepts `type` option, and also accepts `readable`,
`writable` options.

fix #6541
events: do not accept NaN in setMaxListeners
crypto: `randomBytes` is non-blocking

Add NOTE section in documentation, mentioning that `randomBytes` won't
block when entropy sources are drained.

fix #6372
npm: Upgrade to v1.3.15
blog: Post for v0.11.9
events: fix TypeError in removeAllListeners

Check that `listeners` is actually an array before trying to manipulate it
because it won't be if no regular event listeners have been registered yet
but there are 'removeListener' event listeners.
doc: clarify child_process error behaviour

Clarify that an 'error' event may or may not be followed by an 'exit'
event and that it's not safe to make assumptions either way.
blog: npm outage postmortem
stream_wrap: don't call Number::New()

Replace call to Number::New() with a call to Integer::NewFromUnsigned().

Profiling a Real World(TM) application with perf(1) suggests that the
conversion of its argument from integer to double is disproportionally
costly: over 60% of CPU cycles accountable to WriteStringImpl() are
attributable to the conversion.

After changing it to Integer::NewFromUnsigned(), WriteStringImpl()
has dropped from the 'most costly functions' top ten altogether.
doc: http: properly document callback argument
doc: http: document ServerResponse 'finish' event
doc: net: fix typo in example code
build: include postmortem symbols on linux

Previously we were building the symbols, but the linker was garbage
collecting the symbols because they weren't used. Inform the linker
that we want to keep all symbols from v8 around.
tls: reset NPN callbacks after SNI

SNI callback selects a new SSL_CTX for the connection, which doesn't
have NPN callbacks set up.
process: document kill(0), disallow kill(O_RDWR)

The null signal test existed, but only tested the case where the target
process existed, not when it did not exist.

Also clarified that SIGUSR1 is reserved by Node.js only for receiveing,
its not at all reserved when sending a signal with kill().

kill(pid, 'O_RDWR'), or any other node constant, "worked". I fixed this
by also checking for 'SIG'. The same as done in the isSignal() function.
Now the signal names supported by process.kill() are the same as those
supported by process.on().
doc: change constant to consistent
doc: list execArgv option for child_process.fork()
tls: fix pool usage race

When calling `encOut` in loop, `maybeInitFinished()` may invoke
`clearOut`'s loop, leading to the writing of interleaved data
(encrypted and cleartext) into the one shared pool.

Move `maybeInitFinished()` out of the loop and add assertion for
future.
blog: bnoordhuis departure