Gradient Tool Added

Currently, three gradients are supported: linear, mirrored, and radial.
I hope in the future for JEIE to support conical and square gradients. I
found a ConicalGradientPaint class online, but I can't find licensing
information. It can be found here:
http://www.jarvana.com/jarvana/view/eu/hansolo/SteelSeries/3.9.6/SteelSeries-3.9.6.jar!/eu/hansolo/steelseries/tools/ConicalGradientPaint.class?classDetails=ok