event loop hangs at end of execution. document close method

[tjwebb]

I thought I RTFM and didn't see the close() method documented anywhere. This module uses some pool under the hood, and it needs to be manually released. close() method is here:

tilelive-mapnik/lib/mapnik_backend.js

Line 175 in 0fbcb69

MapnikSource.prototype.close = function(callback) {

In case anyone else runs into this.