[SYSSETUP] Disable NEXT button if the fields are not compiled

In my opinion, the way for configuring SYSSETUP could be made less prone to mistakes and simplified: if the user pressed it but no valid data has been written in the fields, at the moment it shows a message box with an error. I suggest to disable the button for advancing if the required fields are empty.

Attached screenshot shows the result.

Attached patch implements it.
After doing it, these strings:

IDS_WZD_NAME
IDS_WZD_COMPUTERNAME

are useless, so they could be removed by all languages.