informs user about incorrect flags

Signed-off-by: Jonathan Berkhahn <jaberkha@us.ibm.com>
T() up new texts for translation

- dot-import i18n, because `gi18n -c fixup` only scan for T(), not i18n.T()

Signed-off-by: Jonathan Berkhahn <jaberkha@us.ibm.com>
handles both "-" & "--" prefix for flag checking

- ignores flag value after `=`

[finishes #69038672]

Signed-off-by: Jonathan Berkhahn <jaberkha@us.ibm.com>
var renaming for readability

Signed-off-by: Jonathan Berkhahn <jaberkha@us.ibm.com>