Request ownership is no longer flaky. Requests are now owned by the code that makes requests, and Requests and the RequestManager co-own RequestHandles. RequestManager disowns a RequestHandle if it's done with it or if Request code reports that it's no longer needed.
All libcurl code has been moved to RequestManager. This is nice because once NOHTTP is removed, we can add any number of RequestManager implementations, for example one for Android.
Client outliving RequestManager is still a problem, this will have to be addressed later.
This fixes bugs like "type\0hello mom" being a property name sim.partProperty accepts and half-fixes bugs like text formatting codes making gfx.drawText exit prematurely.
