introduce function input_and_check
allow list ref parameters for input_and_check
support optional 'ett'
check if 1st command line argument is defined
add hint to separate with spaces
normalize whitespace input
introduce function expand_text to allow flexible alternative expansion
fix wrong push command
add explicit return; use shorter if statement in function
allow alternative 'syv' for 7
add support for tyve (20) and tredve (30)
get rid of single-word case instead of reference to list
normalize strings before checking -- allow number words with and without space separator