* boost::thread mostly gone... still need to get rid of once
everything compiles
* replace boost::call_once
* remove link-time dependency on boost::thread
* first pass at using async
* switch to using async everywhere
* first pass at a MultiFPBReader in c++
includes initial tests
* first pass at multi-threading; untested
* add multi-threaded test
* multi-threaded tversky
* add multi-threaded contains searches
* allow FPBReader::init() to be called multiple times
* add a cleanup() method to clear out whatever memory we are using
* allow the init() call to be pushed to search-time;
this allows calls to the contained init() methods to be run in separate threads
* make ownership of FPBReader pointers optional
add addReader() method
* Add MultiFPBReader python wrapper
* support multi-threaded initOnSearch
* add a couple of more tests
