7-bit refcount might not be enough for large allocations

[hygoni]

For now we use only 7-bit for reference counting.

While I think it is uncommon for small objects to have more than 127 reference count, it might not be enough for larger objects, think about a case where the program allocates, very large array, and increasing the reference count of each element using pointers.

Most importantly, whether we decide to increase it or not doesn't matter, but we need to know how often it's not enough.

Any thoughts?