Update Buffer API

[hs0225]

Compared with node.js, the buffer API of iot.js couldn't support many features. I would like to update it for latest node.js compatibility.

• [ ] Deprecated API : new Buffer(array/buffer/size/string)
• Add API
  • [ ] create : Buffer.alloc, Buffer.from
  • [x] array buffer : Buffer.from(arayBuffer)
  • [ ] [] operator : buf[index]
  • [ ] readDouble, writeDouble, readFlat, writeFloat

To add new features, we need support from JerryScript.

https://nodejs.org/dist/latest-v6.x/docs/api/buffer.html#buffer_buf_index

[zherczeg]

What about enabling ArrayBuffer would be a mandatory requirement for IoT.js? Then the Buffer could be rewritten to use ArrayBuffer as a base.