Control Systems: HP prime app, now with frequency, time domain and root locus plots

[hata]

Hi all, an update to the Control Systems App is now available (version v3.01, attached to the initial post of this thread). User guide is updated as well.

- tested with HP Prime firmware versions 2.1.14425 (2020 01 16) and 2.1.14588 (2021 05 05)
- compatibility with HP prime firmware version 2.1.14588(2021 05 05): fixed syntax errors because of stricter syntax rules
- fixed error with random crashes: moved CAS routines into a separate user program (removed from Control Systems App)
- added demo program 'TestGrid', demonstrating calling grid utility 'DrawGrid'
- added demo program 'CharEquationCoeff', demonstrating calling Control Systems App routine 'RetrieveOneEq'

Hope you like it.
Regards