New subfilter module with multi-pattern search support

Hi all!

There is a new subfilter module. It uses fast Wu-Manber algorithm for multi-pattern search. Probably it would be interesting to someone:

https://github.com/dursegov/nginx-subfilter-module

It is possible to add regular expressions support if it is required, but as a separate engine (i.e. use libpcre instead of builtin Wu-Manber). The combination of them is a good challenge.

The code may still have bugs, since I don't still have a time to write good tests.

Thanks