Merge remote-tracking branch 'upstream/master'

Merge remote-tracking branch 'upstream/master'

* upstream/master:
  [Feature] Add more domains to redirectors list
  [Doc] Add preliminary FANN documentation
  [Feature] Print userdata using tostring if possible
  [Feature] Improve phishing plugin
  [Feature] Improve levenshtein distance function
  [Fix] Repair optional dependencies
  [Minor] Slighlty reduce PHISHING score
  [Minor] Always return constant number of results from lua redis
  [Minor] Improve string to action function
  [Fix] Do not greylist on rejection
  [Minor] Add whitelist for phishing module
  [Minor fix] Limit PHISHING to one shot
  [Minor] Add redirector's TLD to PHISHING symbol options