no warning if package 'dialog' not installed

[der-den]

on a system without package "dialog" the script clear screen and stops w/o any notice
(line 127 calls first time dialog)

[beautberge]

you have to install zenity which includes the gdialog package on newer systems. dialog is no longer used anymore. then you have to change the code in the .sh file at every instance of dialog to gdialog.