line should respect display_zero_tolerance

[janchlebek]

Hi, great work on the card - I love it :)
one suggestion: it is possible to set the display_zero_tolerance to hide the individual device and stop the dot flow. It would be cool if the line could also be hidden in case display_zero_state: true, display_zero_lines is mode: hide and display_zero_tolerance: 5 is set for example - see screenshot: