Remove zero-padding from nowday and whenday (fixes #9397)

This fixes cases where the day component of the when parameter resolved
to a non-zero padded integer under 10, such as "when = 1st at 01"

The comparison against the nowday variable failed consistently since
the date command format used always returned a zero-padded two digit
integer.

The solution chosen is to avoid generating nowday with zero-padding and
remove any zero-padding from whenday parameter using a more thorough
sed pattern which now also removes any non-alphanumeric characters from
the string.