Implement boolean search engine with AND-OR expression.

Implement boolean search engine with AND-OR expression.
Guys, I've finished AND-OR expression. Please check when you have a time. Any suggestions, comments are welcome.
Denis please have a look how you can reuse this one. I suppose you need a last literal at the last tree node (exTree[last].literals[last].test) - it will be the last text after ANR-OR expression.

Also I will add performance tests ASAP.