add (reduced) run_time as child of holidays

Add <run_time> as child of <holidays>
The periods configured by these run_times will be treated as holiday periods (negative run times).

If <run_time> is a child of <holidays> the following Children/Attributes will not be allowed:
@let_run
@once
@repeat
@single_start
@start_time_function
period/@absolute_repeat
period/@let_run
period/@repeat
period/@single_start
at
holidays

Example
<run_time>
<period begin="04:00" end="20:00" repeat="01:00"/>
<holidays>
<run_time>
<weekdays>
<day day="2">
<period begin="04:00" end="10:00"/>
<day>
</weekdays>
</run_time>
</holidays>
</run_time>

Means: Repeat every hour between 4:00 and 20:00 except for tuesdays. On tuesdays repeat every hour between 10:00 and 20:00

The holidays also need to be considered when calculating the <job next_start_time=""> answer and the <calendar> answer