reddit extractors now recursively visit other submissions/posts
linked to in the initial set of submissions.
This behaviour can be configured via the 'extractor.reddit.recursion'
key in the configuration file or by `-o recursion=<value>`.
Example:
{"extractor": {
"reddit": {
"recursion": <value>
}}}
Possible values:
* -1 - infinite recursion (don't do this)
* 0 - recursion is disabled (default)
* 1 and higher - maximum recursion level
