A version that can be merged by fzh
all changes made by fzhedu since last merge.
Merge the changes made by fzhedu and zhanglei since May.27th.

Conflicts:
	BlockStreamIterator/ParallelBlockStreamIterator/BlockStreamAggregationIterator.cpp
	Test/TestMain.cpp
	Test/common/TestNew.cpp
	common/ExpressionItem.h
	common/Mapping.h
	common/Message.h
	common/Schema/Schema.cpp
	common/Schema/Schema.h
	common/TypeCast.h
	common/hashtable.cpp
null supported
Merge refs/linew/upstream/master into li

Conflicts:
	Executor/AdaptiveEndPoint.cpp
	Test/TestMain.cpp
	common/data_type.h
index manager
the code of index has been confirmed.
add Regiester code for sort iterator.
Merge branch 'scdong_master'
newly, change config
makefile
build system added.
add “缺省值”
delete .settings
support limit ;pushing down condition is ok ,but filter is not supported
f
test
add build system and change environment variable.
add third party package.
support:
1.order by support expr
2.limit
3.filter(expressionItem初步)
4.pushing down condition