* rearranged instl_help.yaml commands in alphabetical order.
* added help text to some commands that were missing.
* download_from_file_or_url can check signature or checksum if they are given.
* command createlinks renamed create-links, for easy typing experience.
* command createkeys renamed create-rsa-keys, for easy typing experience and more fitting name.
* parser returns the name of all possible commands.