Allow null default selected values
Added enum filter helper override to pass list items
Made default selection work with enum values
Remove enum conversion to number to use string value by default
Properly update sort field classes in inline filters
Properly update sort field classes on griddly result page refresh
Fix issue with no sort fields
Updated test layout
Merge branch 'master' of https://github.com/programcsharp/griddly
Merge branch 'master' of https://github.com/programcsharp/griddly