Added aliases for std::chrono typedefs (eg. 'Seconds' for
std::chrono::seconds). These aliases are used together with templated
helper functions to replace time_t with std::chrono::seconds for most
cases, in particular for 'modified' and 'expires' values in Response.
It's a premultiplied image. This implies that we were misusing encodePNG
in most cases, as we were passing premultiplied pixels which were then
interpreted as unmultiplied. I changed encodePNG to accept premultipled
pixels, and unpremultiply in the implementations.
The following produces a reference cycle:
var map = new mbgl.Map({
request: function () { ... }
});
map has a reference to the request function, which has a reference to
its closure, which has a reference to map.
Storing a the map options in an internal field, rather than a Persistent,
allows V8 to collect the reference cycle when none of its members have
other references.
By not automatically destroying Request objects after the result has been delivered, we are making sure that we can potentially fire the callback multiple times without adverse effects. This means that you have to hold on to the result of fs->request(), can explicitly cancel it if you don't want to be notified of data changes anymore. Not doing so will monitor the request indefinitely and will prevent the app from exiting.
