Changed file name of .svg to YAPP_Demo_imagesPlane.svg

[mrWheel]

@rosenhauer ,

Great job, again!

I had, in github, changed the .svg file name to the name of the YAPP_Demo_imagesPlane.scad program where it is used.
Just so it is clear the two files belong together.

But that changes seems to be lost.

I have not checked whether the .svg file is used in other Demo programs in which case it is ok to leave the name as it was.

[rosenhauer]

I don't think that it is used in any other example. I got a notification that it had changed when I was creating the merge request and thought I told it to ignore it. Maybe I told it to ignore the change you have not to ignore making the change on my end.

[mrWheel]

Changed the svg filename again.

[mrWheel]

And the changes are gone again ;-)