lets make it possible to parse multiline plain post

Author: John Doe

libraries/ESP8266WebServer/src/Parsing.cpp

@@ -109,12 +109,19 @@ bool ESP8266WebServer::_parseRequest(WiFiClient& client) {
     if (!isForm){
       if (searchStr != "") searchStr += '&';
       String bodyLine = client.readStringUntil('\r');
+#ifdef DEBUG
+      DEBUG_OUTPUT.print("Plain: ");
+      DEBUG_OUTPUT.println(bodyLine);
+#endif
       if(bodyLine.startsWith("{") || bodyLine.startsWith("[") || bodyLine.indexOf('=') == -1){
         //plain post json or other data
         searchStr += "plain=";
+        searchStr += bodyLine;
+        searchStr += client.readString();
+      } else {
+        searchStr += bodyLine;
+        client.readStringUntil('\n');
       }
-      searchStr += bodyLine;
-      client.readStringUntil('\n');
     }
     _parseArguments(searchStr);
     if (isForm){