node: avoid automatic microtask runs

Since we are taking control of the microtask queue it makes sense to
disable autorun and only run microtasks when necessary. Just setting
isolate->SetAutorunMicrotasks(false) would cause _tickCallback() not to
be called.

Automatically running the microtask queue will cause it to run:

* After callback invocation
* Inside _tickCallback()
* After _tickCallback() invocation

The third one is unnecessary as the microtask queue is guaranteed to be
empty at this point. The first only needs to be run manually when
_tickCallback() isn't going to be called by MakeCallback().

Reviewed-by: Trevor Norris <trev.norris@gmail.com>
readline: should not require an output stream.

Passing null as the output stream to readline.Interface()'s constructor
is now supported. Any output written by readline is just discarded. It
makes it easier to use readline just as a line parser.

Fixes: https://github.com/joyent/node/issues/4408
Reviewed-by: Trevor Norris <trev.norris@gmail.com>
buffer: mv floating point read/write checks to JS

Performance improvement by moving checks for floating point operations
to JS and doing the operation on a protected internal function that
assumes all arguments are correct. Still abort if the operation
overflows memory. This can only be caused if the Buffer's length
property isn't the same as the actual internal length.

Signed-off-by: Trevor Norris <trev.norris@gmail.com>
buffer: add generic functions for (u)int ops

Add generic functions for (U)Int read/write operations on Buffers. These
support up to and including 48 bit reads and writes.

Include documentation and tests.

Additional work done by Trevor Norris to include 40 and 48 bit write
support. Because bitwise operations cannot be used on values greater
than 32 bits, the operations have been replaced with mathematical
calculations. Regardless, they are still faster than floating point
operations.

Reviewed-by: Trevor Norris <trev.norris@gmail.com>
util: add es6 Symbol support for `util.inspect`

* `util.inspect` cannot accept es6 symbol primitive
* It will throw exception if do `util.inspect(Symbol())`
* This also affects repl, console.log, etc.

Reviewed-by: Trevor Norris <trev.norris@gmail.com>
Reviewed-by: Chris Dickinson <christopher.s.dickinson@gmail.com>
doc: Update net.markdown

Associates link to dns.lookup() with proper URL.

Fixes: https://github.com/joyent/node/issues/8018
Reviewed-by: Trevor Norris <trev.norris@gmail.com>
Reviewed-by: Chris Dickinson <christopher.s.dickinson@gmail.com>
doc: improve readLine.pause()

The docs for readLine.pause are misleading. I seriously spent hours on this. If
it isn't a bug, at least it should be well documented.

Someone else stumbled on this too:
http://stackoverflow.com/questions/21341050/pausing-readline-in-node-js

Reviewed-by: Trevor Norris <trev.norris@gmail.com>
Reviewed-by: Chris Dickinson <christopher.s.dickinson@gmail.com>
url: fixed encoding for slash switching emulation.

Fixes: https://github.com/joyent/node/issues/8458
Reviewed-by: Trevor Norris <trev.norris@gmail.com>
Reviewed-by: Chris Dickinson <christopher.s.dickinson@gmail.com>
streams: set default encoding for writable streams

This commit adds the ability to set the default
encoding for writable streams.

Fixes #7159
check for valid encoding type
update after rebase