print error and exit if install script is run as root

[Itai-Nelken]

#695
and should fix cases like #694

[Kirill2006183]

# 695
и должен исправить такие случаи, как # 694

The question is solved I had to download the program file sudo apt install file only and started me

[Kirill2006183]

# 695
и должен исправить такие случаи, как # 694

It starts with and without root without errors

[Botspot]

Perhaps this technique would be better? We need the script to detect sudo usage, as well as root usage.

[Itai-Nelken]

It now uses -id -u, I tested and it does work: the error is printed when running with sudo and when running as the root user without sudo.

[Itai-Nelken]

ready to merge in my opinion. what do you say @Botspot?