the yearly copyright sed
add debug log when cancelling a downtime
add last|next_check to orphaned check log output
core: log a debug message when a neb module overrides a check
install: set --enable-idoutils/event-broker to true as default configure flags

fixes #3813
silence some compiler warnings
icinga.spec: fix double %{logdir}/gui/ definitions in icinga and icinga-gui (thx René Koch)

refs #3802

Conflicts:
	icinga.spec
core: refuse to start if neb modules fail to load (Andreas Ericsson) refs #3812

since it will be mandatory to run idoutils once configured, the core
should check if loading was succesful, and otherwise shutdown as well.
Merge branch 'test/core' into next

Conflicts:
	html/docs/de/index.html
	html/docs/en/index.html