Reports days, hours, minutes until a date. The counter does not change while they watch, but it changes every time it is shown.  The embed sequence can be formatted with the usual font and boldness.

Example: " {hd time-until 12/25/2015} until Christmas."   becomes   "43 days and 16 hours until Christmas."

The first argument is a date and time, but it cannot contain spaces.   You can use 'T' to mark the time. Example: '12/25/2015T8am'

The second argument is the format and defaults to 'dh'.

    d -- show days, but will not show 0
    h -- show hours
    H -- show hours only when there is less than a day
    m -- show minutes
    M show minutes only when there is less than an hour

So dh shows days and hours, dH shows just days, then just hours