refs #177

* May be cancelled/scheduled deliberately.
* Are guaranteed to be ready/cancelled before the zone reload.
* Freed on zone teardown.
* DNSSEC force sign was broken as it reused non-force event, fixed that.

refs #173

Relative path resolutsions:
- global keydir is relative to global storage dir
- zone storage dir is relative to global storage dir
- zone keydir is relative to zone storage dir

Based on patch from Kamil Sopko <kamil.sopko@savana.cz>

refs #167

Set to 10800s (see reasoning in issue #155).

refs #155

It is probably inconsistent, just leave it there as it is.

refs #167

refs #145