Update set search context compatability

Fix issues when using default search context

Fix issues when trying to view a single record when filtering

Fix merge issues

Re-add CSS to fix bulk edit checkboxes

Allow setting of custom search context

Update changelog

Add initial support for SS 4.3 (moving search form into GridFieldFilt…

…erHeader)

Make assotiation match for autocomplete fields a little more resilient

Automatically change search fields to autocomplete fields