Tidy up "firewall_schedule_edit.php"

ID statements (DIV tags) cannot take a space separated list of words, so use the underscore character between the month and year.

Make the ID statement in the TABLE tags unique by adding the month and year PHP variables to the ID.

At the end of the month, the TR tag is not being closed correctly, so add a check to see if the day count is greater than the number of days.