Additional cursor moves

[DariuszDepta]

When the cursor is just before the left vertical line, then pressing End should move to the end of the next cell.
When the cursor is just after the right vertical line, then pressing Home should move to the beginning of the previous cell.
When the cursor is at the bottom of the cell, then pressing PgDown should move to the bottom row of the cell below.
When the cursor is at the top row of the cell then pressing PgUp should move to the top row of the cell above.