Extract event listeners to inner classes and provide enable/disable for each

Extract event listeners to inner classes and provide enable/disable for each

Regroup listeners for each listener types in inner classes to ease the
control of actions performed by them.

Mouse wheel listeners actions:
- Zoom
- Horizontal Scroll

Key listeners actions:
- Extend to next/previous marker
- Select next/previous marker

Change-Id: I48d5807a32d9b482b0b424028dfb1406384f273f
Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>