0.9.1

In this release we are greatly increased cloning speed for some objects (up to 2x times). It was made by analyzing constructors and improvements in reference counter code.
Also, there are some small refactorings that slighlty increased speed

Also, we fix 2 bugs, one with possible multiple object copying and second, is more serious, but very rare: safe variant of cloning did not copy readonly fields. Now, this is fixed by some hacks.

And at last, we have checked performance of this library related to others and have found, that DeepCloner is fastest cloning library!