In java code, handle situation when wheel rotation value is zero.

This commit makes sure no zooming occurs in the Java panels mouse
wheel handlers when getWheelRotation() returns a value of zero, which
is possible for some high resolution mouse wheels.

Change-Id: I16d5c008f6c14fd797e68e567800800e9d2ea00e
Merge topic 'java-mousewheel' into master

aef8403d In java code, handle situation when wheel rotation value is zero.