SharedPtr.opEquals

{
	SharedPtr!long x = SharedPtr!long.make(0);
	assert(x != null);
	x = null;
	assert(x == null);
}

{
	SharedPtr!long x = SharedPtr!long.make(123);
	SharedPtr!long y = SharedPtr!long.make(123);
	assert(x == x);
	assert(y == y);
	assert(x != y);
}

{
	SharedPtr!long x;
	SharedPtr!(const long) y;
	assert(x == x);
	assert(y == y);
	assert(x == y);
}

{
	SharedPtr!long x = SharedPtr!long.make(123);
	SharedPtr!long y = SharedPtr!long.make(123);
	assert(x == x.element);
	assert(y.element == y);
	assert(x != y.element);
}