uLUt extended by experimental hash table support.

uLUt extended by experimental hash table support.

The code is based on combination of array indexed
by masked value computed by hash function and GAVL
tree for each of array indexes. This combination
should provide good performance even if the hash
function distribute items non-uniformly for same cases.
Solution has drawback in relatively big memory
overhead required in each inserted item to provide
space for tree node.

The API, above all parameters to UL_HASTAB_CUST_NODE_INT_IMP,
will change probably.

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>