improvement: added support for custom FTP root paths via filter
improvement: return to 1st record in file when applying filters
bug fix: update only selected custom fields didn't work properly
bug fix: update featured image provided by 3rd party add-ons didn't work properly
bug fix: get rid of unused deprecated function add_contextual_help()
bug fix: impossible to move past step 4 when using import template that had import schedules configured
bug fix: last run timestamp not updated if import file is valid
bug fix: no records available when multiple filters are removed
