Add PerformanceInfo in expander status.
Scan, Aggregation, Expander not can print performance status.
Expander PerformanceInfo is now complete. Define _DEBUG_JOIN_ in join
iterator, which is a switch for debug.
Testing hash table scalability and performance.
Merge branch 'master' into ExpandableFramework

Conflicts:
	Test/TestMain.cpp
	common/Message.h
add expander between ResultCacher--->ExchangeEpoll.
Before improve scan scalability
New Scan is completed, waiting for scalability test. -_-
I still cannot figure out the underlying reasong for the bad scalability
of scan->filter without memory copy.
cannot incremental build after updating gcc
The scalability problem in projection scan is partially solved! -_-
In implementing insert-optimized hash table.
Inser optimized hash table is finished, waiting to test.
Partially solved the memory leak problem.
InsertOptimizedHashTable has passed parallel inserting test. -_-
to be continued...
Use slide windows to maintain the instance throughput within a local
stage. However, expand() is not atomic.
In solving the memory leak problem.
A version that can be merged by fzh