Jenkin's "One at a time" hash

This is a C mex interface to the "one at a time" string-to-int32 hash function by Bob Jenkins. I found it clumsy to implement this within Matlab, so I implemented it in C.

For information on the hash function, see
http://en.wikipedia.org/wiki/Jenkins_hash_function
http://www.burtleburtle.net/bob/hash/doobs.html

To use the function, first
mex jenkinshash.c
then simply
h = jenkinshash('Some string');
If the argument is a matrix, one hash is returned for each row.