Parameters file for Handy Covers

This is a remix for a great parametrized handy cover SCAD file of thing 2561342

As I have 4 different phones in my family I've created ca 10 scad files (e. g. various designs with rectangles, holes, joining sensor and camera opening, etc. I destroyed some files accidently by calling "save" at the wrong moment, ...
Finally I could not remember which one worked an which did not :-(

Then I decided to separate the variable data (the part before [Hidden] comment) from the basic design which must not become changed.

The parameter file (e.g. "HUAWEI-P-Smart-V4_param.scad") becomes included as 1st statement in the basic scad file ("Phone_cover_base.scad"), which looks like:

/******** Include model defintion **********  Insert below the file which defines all   parameters for your specific phone model *******************************************/ include <HUAWEI-P-Smart-V4_param.scad>/* [Hidden] */...

The basic idea is to provide some sort of library for various handy covers. Due to the parametric design only the device specific parametric file must be created and included into the base cover file.