demo/example run

[marcelgoldstein]

add an option to run showcase the image comparing capabilities by running a demo mode which

1. copies some sample images to a folder in the users temp folder
2. add the folder path to the "folders"-selection
3. start the compare run
4. opens the results view
5. activating the "extermination mode" and deleting the smaller image of an duplicate
6. closing the results view
7. finish the demo run by clearing all results, folder selections und deleting the folder in the users temp folder

All these steps should be done automatically and/or by guiding the user to take the input/clicks by highlithing the buttons or dimming all other UI. Step by step guiding through and giving descriptions of what is happening while it is happening.

[marcelgoldstein]

this issue could use the framework described in issue #29