A version that can be merged with master
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
add build system and change environment variable.
add third party package.
little change for beauty
add create projection while create table
add mysql connection pool and libeasy rpm to thirdparty.
add O0 compile optimization.
blocked in connection 2.
blocked in connection 2, and we need sovle the simple return result.