* Add cache implementation
* Remove old ASEqualityHashHelpers
* Some more ASEquality and ASEqualityHashHelper cleanup
* Add cache for text renderer in ASTextNode
* Move from C++ LRU renderer cache to NSCache based renderer cache
The crash happens in the placeholderImage of ASTextNode. The node is not visible in the time it try to get the `placeholderImage` and so the `visibleRange` has count 0 and a crash happens while accessing the first object of an empty array.
