Updated code for node v4 compilation

[ldiqual]

@hulbert

Compiles on node v4.2.2.

Build instructions:

$ nvm install v4.2.2
$ nvm use v4.2.2
$ npm install node-gyp
$ ./node_modules/.bin/node-gyp configure
$ ./node_modules/.bin/node-gyp build

Major steps used to convert to node v4:

• Updated to nan 2.1.0
• Used this script io.js v3 preparation nodejs/nan#376 (comment) to convert most of the codebase
• Most nan values were MaybeLocal instead of Local (which is kind of an optional -- see https://github.com/nodejs/nan/blob/master/doc/maybe_types.md#api_nan_maybe_local), force converted them to Local with ToLocalChecked() (unsafe).
• args was renamed to info
• Rest was just a matter of reading more nan doc

[hulbert]

@ldiqual awesome! Thanks for tackling this.

Most nan values were MaybeLocal instead of Local (which is kind of an optional -- see https://github.com/nodejs/nan/blob/master/doc/maybe_types.md#api_nan_maybe_local), force converted them to Local with ToLocalChecked() (unsafe).

Any risk on this change to things crashing?

[ldiqual]

@hulbert My guess is that the behavior doesn't change between then and now: if you can't get a local handle, then it crashes. The new behavior of nan makes it so you have to unwrap the optional, the previous behavior produced an "implicit" optional (which would fail with a null reference if used). That's only my guess, my v8 and c++ skills are really rusty.

Ultimately, we'll want the original author of the library to confirm this.

[jdsadow]

@ldiqual @hulbert what's the status on this, guys?

[hulbert]

@jdsadow will discuss in Trello

[rregue]

I think we should close this.