Remove schedule_new_event and event_types all togheter

schedule_new_event is the last part that handled wall time in the event
queue interface (expect reading directly from the timed_event
structure, damn checks.c), which means we should remove it, if we want
to use a monotonic clock instead of wall time for the event queue.

Using a monotonic clock will make the time-skip-detection-function from
stone age totally irrelevant.

But we're not there yet... Check exeuction needs to be rewritten a bit
before, so it doesn't need to read time from the event, and probably
also not use wall-time for check exeuction logic.

This will however also break the API used in some modules for executing
timed event. Those modules should be updated to schedule_event anyway.
A wrapper for schedule_new_event, that uses schedule_event as a backend
would be useful if backward compatibility is expected.

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