[TIMOB-3275] Scrollable view caching improvements

(from [96844c9ddddbabc678c3a2a03037f7c2dc50861c]) [#3275] More accurate scrollableview cache rendering code. https://github.com/appcelerator/titanium_mobile/commit/96844c9ddddbabc678c3a2a03037f7c2dc50861c"> https://github.com/appcelerator/titanium_mobile/commit/96844c9ddddb...

(from [14fa43d620494f6a10944bb03900d9434715560e]) [#3275] Significant scrollable caching improvements. https://github.com/appcelerator/titanium_mobile/commit/14fa43d620494f6a10944bb03900d9434715560e"> https://github.com/appcelerator/titanium_mobile/commit/14fa43d62049...

This was a red herring from scrollable view improvements. Instead, it's just that our view rendering code is massively inefficient; going to mark for 1.7.0 as a potentially late-term improvement and assign to Reggie for triage.

The previous two commits take care of the issue from the scrollable view side of the equation.

Tested with the following combination:
Build 01937daa0e^ Build Master Titanium SDK version: 1.7.0 (03/07/11 10:54 4fb5ed1)
iPhone 3g 3.1.2 slight stall when scrolling Same as previous build
iPad 3.2.2 scrolls smoothly Same as previous build

I have ran the test application against the above builds and device, the only difference that I have encountered is that Build 01937daa0e^ will crash after scrolling through ~10 images and the new build will not crash. The slow scrolling seems to be device specific and not the iOS.

I can attest to the scrolling smoothness issues. Tested on iPhone 3GS running latest iOS version and iPad running iOS 3.2.2. On iPhone, seems to stall about mid-way through the animation - looks like it is trying to cache the new image during the animation, when it should be doing that after the animation is complete. On iPad, scrolling seems a bit smoother, but still stalls slightly mid-animation. Also, I am noticing no differences between different builds in this aspect.

Additionally, the app still crashes after scrolling through a number of images (the number is dependant on image dimensions, which makes sense - bigger images require more memory to be allocated). Unfortunately, my app also crashes with the latest build, so the caching improvements didn't seem to fix the memory leaks. Possibly a gc issue?