Manage RowOrientedCursorBase#jump(). In the new order of things, calling
jump can only occur when 1) the cursor is ACTIVE/IDLE, and 2) resets the
state back to ACTIVE, so next() returns a actual row. 

In IndexCursorUnidirectional, move the endKey setup from Initializer to
open(). This accounts for calling close()/open() to set up the endKey
properly, but not manging it when calling jump().