config: Fix resolving macros in command arguments.
config: Fix looking up host custom attributes.
config: Temporarily set hostname for services.
config: Fix attribute lookup functions.
config: Fix arguments for hostchecks.
Implement setgid/setuid support.

Fixes #3841
Set group before user.
Fix logging performance problem.
cluster: Make log replays non-blocking.
cluster: Don't replay log messages twice.
cluster: Another log replay fix.
cluster: Yet another fix.
cluster: Re-open logfile after log replay.
Add debug message.
Fix: Cluster log files were not properly removed when an instance has no peers.
Change log level for a debug message.
cluster: Remove old logs before reconnecting.
Config Conversion: Add proper check_command detection in templates.
Config Conversion: Detect hosts w/o services and properly add hostcheck.

it's ugly but it works. requires code refactoring.
cluster: Implement domain support.