tmf: Bug 451240: Mouse wheel inactive on time graph scale and scroll bar

tmf: Bug 451240: Mouse wheel inactive on time graph scale and scroll bar

- Add a mouse wheel listener to the time graph scale to zoom

- Remove the mouse wheel event filter that was added when time graph
control had focus, and replace it with a listener to prevent horizontal
scrolling on mouse wheel events.

Change-Id: Ib2bb917a8e447929843117e9cf55eadac3ed7e6d
Signed-off-by: Patrick Tasse <patrick.tasse@gmail.com>
Reviewed-on: https://git.eclipse.org/r/37311
Tested-by: Hudson CI
Reviewed-by: Matthew Khouzam <matthew.khouzam@ericsson.com>