Run OSX builds in Travis CI

Now that io.js and Node.js have converged these comments make no
sense.

Add Node.js 4 to AppVeyor

Replace pangyp with node-gyp

We originally adopted pangyp as a tempory work around for iojs
support. This and more has been added to node-gyp and as such
pangyp has been deprecated.

Fix crash in List::SetValue() etc. when trying
to add a bare JavaScript object.

Check for bare objects in lists and maps in test.

Don't use C++ exceptions in the binding code.

Make Travis CI to report failures on Node.js 4.0

In the unlikely event libsass gives us the
value we don't understand use V8 exception
to report failure and exit before calling
a user-defined custom function.

XXX We do not have currently any way
    to test this (that would require mocking
    libsass).

::construct() methods may return NULL and
indicate an error in the returned error value.

This method uses Sass error value
as a vehicle to report the error message,
but returns NULL to indicate constructor
failure.

This is used to tell successful creation
of the Sass error object from the constructor
failure, where no valid Sass object can be
created.

Make the build process output actually
useful.

Update to the new Travis CI infrastructure.

http://docs.travis-ci.com/user/migrating-from-legacy/#Why-migrate-to-container-based-infrastructure%3F

Update reference of 'multi-file' to 'directory'

Standardise on cross-spawn for spawning child processes

The multi-file terminology is unintuitive and could be seen as
suggesting we support multiple input files, when in fact we're
describing directory support.

Empty data string is not a file name

There a known issues with `spawn` on Windows i.e. joyent/node#2318.
As a work around we sometimes use
[cross-spawn](https://www.npmjs.com/package/cross-spawn). We will
move all usage of `spawn` to `cross-spawn`.
Closes #1015.

Revert "Workaround the segfault that occurs when used with fsevents"

This reverts commit 3166b613.

Ensure we have nan@^2.0.8

This is to make sure binaries affected by
https://github.com/sass/node-sass/issues/1107 are never built

Remove C++11 feature in order to be
able to compile against libstdc++.so.6.0.9
on MacOSX.

Allow to link the binding against
oldish libstdc++.6.0.9 installed on MacOSX
(from gcc 4.2.1)

Workaround the segfault that occurs when used with fsevents

fsevents@0.3.8 introduces a segfault that manifests when used with
node-sass. fsevents is widely popular. As a mitigation we've added
fsevents@0.3.7 as an optionalDependency.The intention here is the
prevent users install node-sass@3.3.x and fsevents@0.3.8 by using
npm's deduping behaviour.

Intended to fix https://github.com/sass/node-sass/issues/924