This is to avoid logging a 'slow' request when the source of delay is the viewer in processing a response.
This is not something we can do much about on the server end - it's server-side delay that we're interested in.
To ensure consistency, this commit also had to refactor and simplify inbound non-poll network request handling, though there should be no functional change.
IOSHttpResponse no longer exposes the Send() method, only classes in OpenSim.Framework.Servers.HttpServer should be doing this.
Only the GetTextureHandler was sending its own response. Now it leaves this to BaseHttpServer, like all other core handlers.
This is required for the substitution of different HTTP servers or the newer HttpServer.dll without having to commit to a particular implementation.
This is also required to write regression tests that involve the HTTP layer.
If you need to recompile, all you need to do is replace OSHttpRequest/OSHttpResponse references with IOSHttpRequest/IOSHttpResponse.
