Convert to unsigned long to remove warnings.

[dapostol73]

Can you add unsigned to the this line, it will remove warnings about comparing an unsigned long with a signed long at line 1604 & 1655

unsigned long timeoutTime = millis() + TIMEOUT_MS_SERVERRESPONSE;

megaatmega2560\ThingSpeak\src\ThingSpeak.h:1604:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
if(millis() > timeoutTime){
megaatmega2560\ThingSpeak\src\ThingSpeak.h:1655:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
if(millis() > timeoutTime){

thingspeak-arduino/src/ThingSpeak.h

Line 1600 in 9aceb14

long timeoutTime = millis() + TIMEOUT_MS_SERVERRESPONSE;