Specify default values for color arguments

[elfenlaid]

Follow up to the ArgumentParser migration and a related conversation #14 (comment)

The change leverages ArgumentParser's default values to generate a more insightful help message

Without default values:

  --color <color>         Specify a valid hex color code in a case insensitive format: '#rrggbb' | '#rrggbbaa'
                              or
                          Provide a named color: 'snow' | 'snow1' | ...
                          Complete list of named colors: https://imagemagick.org/script/color.php#color_names
  --tint-color <tint-color>
                          Specify a valid hex color code in a case insensitive format: '#rrggbb' | '#rrggbbaa'
                              or
                          Provide a named color: 'snow' | 'snow1' | ...
                          Complete list of named colors: https://imagemagick.org/script/color.php#color_names

With default values:

  --color <color>         Specify a valid hex color code in a case insensitive format: '#rrggbb' | '#rrggbbaa'
                              or
                          Provide a named color: 'snow' | 'snow1' | ...
                          Complete list of named colors: https://imagemagick.org/script/color.php#color_names
                          (default: randomly selected from #EE6D6D | #A36DEE | #4C967E | #3B8A4B | #CABA0E | #E68C31 | #E11818)
  --tint-color <tint-color>
                          Specify a valid hex color code in a case insensitive format: '#rrggbb' | '#rrggbbaa'
                              or
                          Provide a named color: 'snow' | 'snow1' | ...
                          Complete list of named colors: https://imagemagick.org/script/color.php#color_names (default: white)

Note the (default: value specification at the end of each help entry

[arthurpalves]

💯