GUI and first' page's some fields validation.

   So, looks like now this is fully working GUI and as it was written in issue #6, first page of GUI ( actually second - first one is greetings) is now connected to main RPG class and sends him values from LineEdit of 'License', 'URL', 'Vendor' and 'Packager'. And seems like issues #5 #6 and #7 can be closed.