Bump node module version to 15

Allow NODE_MODULE_VERSION to be overrided.

Prototype of V8::TerminateExecution has changed in latest V8.

Prototype of V8::TerminateExecution has changed in latest V8.

Export modules' DSO constructors.

We need to reference DSO constructors to make sure they can actually be
linked to the final binary, see http://git.io/DRIqCg.

Build with debug information on OS X.

Build with debug information on OS X.

Build with debug information on OS X.

Guard against NULL in ErrName.

The uv_err_name would return NULL on unknown system error, which then would
crash V8 by creating string from NULL.

Add on_watcher_queue_updated callback for loop.

This callback is called when loop's watcher queue changes, when polling
kqueue in new thread, we need to get notified when there are new events
needed to be watched.