New option to: add(record, first)

If first is true, the new record/s would be at the beginning of the grid.
If false or not defined, would be at the end of the grid (actual behaviour)
Fix issue 771

Fix refresh for custom fields.
Merge pull request #770 from natxocc/patch-2

New option to: add(record, first)
Merge pull request #772 from AlexKovynev/patch-1

Fix issue 771
Small fixes