Merge pull request #1097 from emmanuel-keller/master

Bug fixes and improvements
Merge pull request #1101 from emmanuel-keller/master

v1.5.8 change log
Merge pull request #1108 from emmanuel-keller/master

Implements #1105
Update how_to_use_variables_with_database_crawler.md

Language/clarity corrections.
Merge pull request #1113 from emmanuel-keller/master

Fix #1102, implements #716
Implements #1114