ENYO-2111: clamp index value for panels before indexChanged is called so inherited kinds are also clamped
Also, modify previous/next to do their own clamping when in this.wrap mode since clamp won't change things.

Enyo-DCO-1.1-Signed-Off-By: Ben Combee (ben.combee@lge.com)
Change code to use enyo.Object.bindSafely

Enyo-DCO-1.1-Signed-Off-By: Ben Combee (ben.combee@lge.com)
Merge pull request #13 from enyojs/bindSafely

Switch code to use enyo.Object.bindSafely