Remove Load control

Load control is an undocumented feature, flagged as experimental,
without tests, that looks like a proof-of-concept idea implemented long
ago without maintenance. The implementation span through the entire
source, and hooks in to almost everywhere. Using this feature ends up
with a big warning that it is an experimental feature.

Removing this should be quite safe, and will remove lot of dependencies
between modules, and would simplify the specification of API:s between
modules a lot.

Removing it at this point is due to the hook in should_run_event method
in events.c that needs to be refactored to end up in the host and
service check event handlers.

Signed-off-by: Max Sikstrom <msikstrom@op5.com>