Improve csv dumper
Change default connection timeout from 10 to 3
Add MysqlCSVDumper class to prepare CSV dumps for import to MySQL
Fix bug in RexResultList.text method
Now spider does not complete the work if task generator is active
Add fallback-methods: custom methods that are called when task failed
Fix the method of detection valid images in MongoObjectImage data
shortcuts
Add `lower` parameter to grab.tools.russian::slugify method
Add grab.util.log::print_dict method for fuzzy displaying of dict
objects in console