* Make ResultCache max_size configurable
fixes#463
* Add tests and docs.
* fix documentation...
...adapt the source, not the auto-generated man pages themselves as
requested in #544.
* fix typo.
$ grep -rn aborttimeout linkcheck
linkcheck/configuration/confparse.py:167: self.read_int_option(section, "aborttimeout", min=1)
linkcheck/configuration/__init__.py:184: self["aborttimeout"] = 300
linkcheck/director/aggregator.py:173: timeout=strformat.strduration_long(self.config["aborttimeout"]),
linkcheck/director/aggregator.py:200: timeout = self.config["aborttimeout"]
config["aborttimeout"] is only set from aborttimeout and is the only
value used by Aggregate.abort().
