Faster CPMutableArray removeObjectIdenticalTo:.

About 6-8X speedup by skipping all the `indexOfObjectIdenticalTo:` calls and going straight to JS `indexOf`.
Fixes #829. Improve - CPView removeFromSuperview performance.

In the modified test described in #829 performance improves by at least 30% and that's with a significant addSubview: component diluting the test.

This change should improve outline and table view performance.