Add sequencer class - replacement of the cache class
WIP: working on new in-memory cache
WIP: working on a Sequencer implementation
WIP: working on Sequencer class
WIP: first test for Sequencer class
WIP: more tests for Sequencer
WiP: working on sequencer syncronization
WIP: working on synchronizaton between searcher thread and worker thread
WIP: Simple search for Sequencer implemented, tests broken
Change semantics of the add/merge methods. Tests are OK now.
Add test for Sequencer::search
Backward direction scanning implemented for patience-sort index
Old cache implementation removed, sequencer is used instead
LimitCounter removed, tbb dependency no longer needed, cache.h(cpp) renamed to sequencer.h(cpp).
Sequencer perf-tests (not organized yet)
Merge branch 'patience-sort'