CSTMENU: multilevel custom menu with soft keys

[berserkerbernhard]

I didn't got it working the first time.

Please run the program (CSTMENU) first before pressing the Menu key. It's not obvious from the manual.

Now it's playtime. If this works as expected, I can move most of my homemade applications from my 50G to the Prime.

Kind regards

Bernhard