added `read-components` compatibility

https://github.com/paulmillr/read-components
Merge pull request #573 from KATT/master

Added `read-components` compatibility
Corrected filter-external docs. Fixes #571
Add pager documentation about processing & extra values. Fixes #576
grouping widget demo update
grouping widget name now saves after callback. Fixes #514
pager processAjaxOnInit works with jQuery objects. Fixes #572
Destroy will now maintain applied theme

with false flag set: $("table").trigger("destroy", [false]);
No js error when getFilters targets a non-tablesorter table
version bump