Replace the int() with helpers.tryInt() in config save function

During my test I could not save the config multiple times. The Save-Button simply never returned, because some values could not converted to int and had thrown an exception.

I replaced all int() with helpers.tryInt(). Now the GUI correctly shows an error when an value is not valid and you can change the setting.

Maybe you want to add a second parameter for some values before merging the pull request, because you can add a optional second parameter to helpers.tryInt() that will be returned when the convert doesn't work (default is 0, without the second parameter). For some 0 will not be optimal value in such a case...