Add an "M" option for Maintenance on the calendar

If we are booking just about every day of the week, like in the summer, sometimes we block out a day for maintenance. This is especially true when there is only one day open between a long string of bookings. If we enter that day like normal, then it shows up as a T for turnaround.
A little confusing to our housekeeper. I would propose being able to select it as an “M” for maintenance. The other benefit for the owners and booking agents, is that if they see an M, they know that this is typically a voluntary day blocked out and could be reversed for a paying Customer.