implement recommendations from reviewers

* simplified transition bugfix
* removed cast same type
* isIp parameter changed to pass-by-reference, to avoid copy constructor

wled00/wled_server.cpp

@@ -21,7 +21,7 @@ static const char s_accessdenied[]   PROGMEM = "Access Denied";
 static const char _common_js[]       PROGMEM = "/common.js";
 
 //Is this an IP?
-static bool isIp(const String str) {
+static bool isIp(const String &str) {
   for (size_t i = 0; i < str.length(); i++) {
     int c = str.charAt(i);
     if (c != '.' && (c < '0' || c > '9')) {