Lovelace: Improve show period of statistics-graph card

Instead having a minimum period of 1 day to show (with “days_to_show” variable) in the statistics-graph card, i think it coud be good to have another variable called “hours_to_show” to reduce the scope to a minimum of 1 hour.
In addition, adding a boolean “show_current_day” variable could be good too (to only show the current day from midnight to current time).