InputText: Fixed a tricky edge case, ensuring value is always written back on the frame where IsItemDeactivated() returns true (#4714)

Altered ItemAdd() clipping rule to keep previous-frame ActiveId unclipped to support that late commit.

Also, MarkItemEdited() may in theory need to do:
if (g.ActiveIdPreviousFrame == id)
        g.ActiveIdPreviousFrameHasBeenEditedBefore = true;
But this should already be set so not adding now.
5 files changed