Added "Transfer-Encoding:Chunked" support when your content length is unpredictable.

[berkanuslu]

When you're working with streams, especially if different threads control this stream, you might not know content-length, but you can transfer your data with Transfer-Encoding: Chunked. It has been implemented based on https://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html documentation. I have created an example for transferring your data with chunked. Also, I have added an example of a download file from the internet with the content receiver and ofstream.

[evg82]

Awesome! I ask for this function some days ago. I will try it tomorrow becose i have all my app code ready to use it.

[yhirose]

@berkanuslu, thanks for your pull request. However, I feel the pull request is too big to merge for me. Also I did quick check and I have already found two problems:

• It breaks KeepAlive unit test
• I removed the recent memory leak fix. (Fix memory leak due caused due to X509_STORE #671)

So I am not planning to merge it anytime soon though, at least I understand demand of chunked transfer encoding on client side in addition to the existing server side implementation (https://github.com/yhirose/cpp-httplib#chunked-transfer-encoding). Anyway, thanks for your contribution!

[berkanuslu]

@yhirose, thanks for your reply. I don't know what breaks the KeepAlive unit test, but I'm working on fixing this. I just wanted to share this code blocks with the community. But you're right, and it's a little bit big to merge it. It's up to you. By the way, I have closed the pull request. I will split it into a small piece of pull requests.