Added any_cast_test, don't throw on failed pointer cast, equality operator#6

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eligt wants to merge 3 commits intothelink2012:masterfrom

Commits on Oct 19, 2017

Added any_cast_test, which returns false if value can't be cast, instead of throwing an exception
eligt
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Don't throw exceptions when any_cast fails to cast a stored pointer value, simply return nullptr
eligt
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Added equality operator to compare different any objects
eligt
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