Description of cdb reading and format.

CDB is a disk based hash table format which uses a linear array after
a collision.

CDB Hash function:

salt = 5381
hash = salt
for each character in string
	hash += hash << 5
	hash ^= current character

Up to 256 keys at the start of the file in 8 byte records.
Each record consists of:

4 byte hash of the key
4 byte hash length 

Upper 3 bytes are used to calculate offset to data, when %'d with the
has length found in the loaded record.
Lower 8 bits of calculated hash is used as offset to initial 8 byte record.

Offset of the next hash table in the file and then the offset into the
hash table mod the length of the hash table.


Format:

Offset		Contents
0-2048		8 byte records as described above

