Review URL: http://codereview.chromium.org/3045016

Stops Valgrind from complaining about uninitialized memory access.

Change scope to context in REPL docs.

support for
- long messages
- spaces in header fields

Also silences a compiler warning about deprecated conversion from const
char* to char*.

& has higher precedence than ==, making this a noop. Use the less
error-prone S_IS* macros instead. Found by clang.

The old definition was off by one byte on BSD. Also simplify
ADDRESS_TO_JS because sun_path is always zero-terminated now.

Added ability to pass offset to buffer write and toString methods as a string, i.e. '2' and encoding as anything

Fixed format, so it wouldn’t blow up if %d argument is null or undefined + ensure that numbers will be numbers

There might be an off-by-one on the returned value.

Before there was this comment:
  Can't strip trailing slashes since module.js incorrectly
  thinks dirname('/a/b/') should yield '/a/b' instead of '/a'.
But now, such thinking is corrected.

- Buffer.toString('ascii', 0, 0) incorrectly returns the entire contents
  of the buffer. Fix this.
- Provide similar behavior to Buffer.write() and Buffer.copy() when
  dealing with 0-length in valid and invalid byte ranges.

This way, require("/foo") will work if there is a "foo.js", or a file named
simply "foo" with no extension.

Callbacks should always be the last argument.