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 v