Increase catalog zone entries hash table's bits size

Increase catalog zone entries hash table's bits size

The hash table implementation in the current branch does not
support automatic resize operation, so the initial value of
the table should be chosen carefully.

Catalog zones entries hash table's size is currently only 4 bits,
which is very low for a catalog zone with thousands of entries,
and causes CPU consumption spikes when working with the hash
table to add/delete/search entries.

Use 16 bits instead, which should make working with big catalog
zones much faster at the expense of slightly higher memory usage,
i.e. 512 KiB for a 64-bit system for each catalog zone.