[TIMOB-26586] iOS: Animation curve ease-in/ease-out does not auto-reverse correctly

*Summary:* A view animation with "autoreverse" set to true and a "repeat" of 0 (the default) will not correctly reverse the animation when using "curve" Ti.UI.ANIMATION_CURVE_EASE_IN or Ti.UI.ANIMATION_CURVE_EASE_OUT. The animation incorrectly uses the same curve when performing the reverse animation. If "repeat" is set to 1 or higher, this issue will only happen on the final/last repeated reverse animation. This issue won't happen on prior repeated animations. *Expected Behavior:* When the curve is set to Ti.UI.ANIMATION_CURVE_EASE_IN, then the reverse animation curve is supposed to be Ti.UI.ANIMATION_CURVE_EASE_OUT. When the curve is set to Ti.UI.ANIMATION_CURVE_EASE_OUT, then the reverse animation curve is supposed to be Ti.UI.ANIMATION_CURVE_EASE_IN. The above is how it works in HTML5 "reverse" animation. See... https://developer.mozilla.org/en-US/docs/Web/CSS/animation-direction#Syntax *Cause:* Titanium's iOS code generates its own reverse animation to work-around an Apple bug. The issue is that the reverse animation uses the same "curve" as the forward animation. This is where the reverse curve should be applied instead. https://github.com/appcelerator/titanium_mobile/blob/master/iphone/TitaniumKit/TitaniumKit/Sources/API/TiAnimation.m#L412