[Cin] AppImage for CinelerraGG testing

[Andrea paz]

@MatN
Thanks for the explanations.
Calf plugins are read only at the first start of CinGG compiled, no
more in subsequent sessions. AppImage are read every time. Maybe this
is the reason for the slightly longer start?
I didn't understand Note1, what shell commands should I test?


@Phyllis
> "BUT, I hope you continue to do your builds and GIT checkout..."
Yes, of course.