Merge pull request #6704 from efuss/fix/scheduleddowntime1

Put newly configured already running ScheduledDowntime immediately in effect

diff --cc lib/icinga/legacytimeperiod.cpp
Simple merge

diff --cc lib/icinga/legacytimeperiod.hpp
Simple merge

diff --cc lib/icinga/scheduleddowntime.cpp
Simple merge

diff --cc lib/icinga/scheduleddowntime.hpp
Simple merge