[FIX] High memory use by the client

[dinccey]

The client uses a lot of memory when sending a large response body / receiving a large request body. The issue is caused by loading the entire request or response body into memory which doesn't appear to be needed. The following commit resolves the problem. Might need some more testing but it appears to be working the same as before with much less memory use.

08fd5ce

The bulk of the code additions comes from copying functions from libraries to be able to modify them.

[dinccey]

Pull request merged