Grouping: Add "monthyear" grouping to dates. Fixes #744
Core: get column index from data-attribute when sorting
Core: Add widgetClass option & fix debug logs for applying widgets. Fixes #743
RepeatHeaders: now works with filtered & nested tables
Core: aria-labelledby attribute no longer added with nested captions
uitheme: add method to remove previous theme
Core: update widgetClass option matching. See #743
Pager: widget cleanup & only use last search data
Uitheme: fix multiple header row sort icons
Themes: Fix zerba striping in nested tables
StickyHeaders: works with nested tables & modified options. Fixes #724