Description: Checks if the input IPs are valid and if the first IP is "smaler" than the second. Then adds an error message to the message manager in case of an error.
Parameter:
firstIp: The first IP marking the begin of the IP range.
lastIp: The last IP marking the end of the IP range.
Returns:
true, if the IPs are correct and the first IP is "smaler" otherwise false.
