Support for standalone ASIO

[Lssikkes]

I took a stab at porting the new ASIO backend to using the standalone ASIO library, but it was not as trivial as I'd hoped (posix::descriptor not available, nor is the timer, though there's an alternative using std::chrono). Are there any plans for standalone ASIO support?

[yangxingpping]

@Lssikkes I am also want something like this, can you share the code. or something describe in this
https://github.com/uNetworking/uSockets/issues/14

[Lssikkes]

@yangxingpping Unfortunately haven't tried further, currently just using libuv on windows and the native implementation on linux. Seems to work well enough.

Asio support is aimed at Boost users and eventually standard C++.