New version of the backward reference search code.

The new	interface of the backward reference search
function makes it possible to use it in	a streaming
manner.

Using the advanced cost model and static dictionary
can be turned on/off by	template parameters.

The distance short codes are now computed as part of
the backward reference search.

Added a	faster version of the Hasher.
Merge pull request #9 from szabadka/master

New version of the backward reference search code.