Fixed crash on invalid ip and or port change

[ThatGuyThimo]

When changing the ip address or port number to an invalid value on the next restart the app would crash do to the loaded invalid value'(s),

This pull requests checks if: the ip address is not blank or white space, the ip is an valid ip address, it is a resolvable hostname. It also checks if the ports are not smaller than 1.

Let me know if the code needs any modifications.