* Rework WiFiClient

Rework WiFiClient to correct error where making a copy of a WiFiClient object resulted in the socket being closed prematurely.

Added loop and select to write to handle/prevent EAGAIN errors.

* Rework WiFiClient to use shared_ptr

Rework changes to utilize shared_ptr rather than manually maintaining reference count. 

Revert changes to write

* Incorporate comments from review

Move WiFiClientSocketHandle and fd() into WiFiClient.cpp