improve robustness when heap is low

* customMappingTable: allocate using calloc instead of new (new will throw exception if nor enough heap)
* fixing a few minor memory leaks
* ws.cpp: catch out-of-memory in sendLiveLedsWs
* ws.cpp: change interval to 80ms (120 ws very slow...)

wled00/ntp.cpp

@@ -8,7 +8,7 @@
 //#define WLED_DEBUG_NTP
 #define NTP_SYNC_INTERVAL 42000UL //Get fresh NTP time about twice per day
 
-Timezone* tz;
+Timezone* tz = nullptr;
 
 #define TZ_UTC                  0
 #define TZ_UK                   1
@@ -38,7 +38,7 @@ Timezone* tz;
 byte tzCurrent = TZ_INIT; //uninitialized
 
 void updateTimezone() {
-  delete tz;
+  if (tz) {delete tz; tz = nullptr;}
   TimeChangeRule tcrDaylight = {Last, Sun, Mar, 1, 0}; //UTC
   TimeChangeRule tcrStandard = tcrDaylight;            //UTC