ClientContext (tcp) updates (#5089)

* +sync, get/set default nodelay, sync

* default nodelay=1

* update flush()

* fix return value

* ClientContext: put things together

* ClientContext: fix debugging messages

* WiFiClient: move static members out of the class, add comments

* remove circular dependency

* parameter and return value for Client::flush&stop, flush timeout raised to 300ms

* tcp flush: restart timer on ack receive

* OTA protocol needs setNoDelay(true)

* fix Ethernet with Client changes

* 1 line unredable -> 5 lines readable code

* doc

* Update client-class.rst

* Added details for getters

libraries/ESP8266WiFi/src/WiFiClientSecureAxTLS.cpp

@@ -271,12 +271,12 @@ uint8_t WiFiClientSecure::connected()
     return false;
 }
 
-void WiFiClientSecure::stop()
+bool WiFiClientSecure::stop(unsigned int maxWaitMs)
 {
     if (_ssl) {
         _ssl->stop();
     }
-    WiFiClient::stop();
+    return WiFiClient::stop(maxWaitMs);
 }
 
 static bool parseHexNibble(char pb, uint8_t* res)