When building using the new NDEBUG option recently added, the assert()
macro is defined to nothing. This leaves a few variables unused in the
WiFi stack causing compiler warnings. Add in empty casts to remove
these warnings. Does not affect actual assert use when NDEBUG is not
defined.
* Suppressed -Wunused-parameter and -Wunused-function by casting to void unused identifiers.
* Explicit initialization of all fields to suppress -Wmissing-field-initializers.
* Fixed signed/unsigned integer comparison.
* memset initialization of structs.
* More -Wunused-parameter fixes.
* WiFiClient: use DataSource for writes
* ESP8266WebServer: delegate writing to WiFiClient
* ESP8266WebServer: set write timeout before sending content
