Prevent data from leaking into a new Buffer
Prevent data from leaking into a new Buffer

Fixes a leak per the Node.js docs @ https://nodejs.org/api/buffer.html#buffer_new_buffer_size

Ideally Buffer.alloc() would be utilized in place of new Buffer(); however, I'm not sure which version of Node introduced that API so for backwards compatibility sake I added an API check and fallback to `buf.fill(0)` for older Node versions.
xdenser/node-struct