Merge pull request #10 from HuiLi/master

合并更新
Merge pull request #11 from HuiLi/master

合并更新
Merge pull request #12 from HuiLi/master

合并更新
更新Not、Once、BitNot、If、IfNot、IsNull、NotNull、Column
Merge pull request #13 from HuiLi/master

合并更新
Merge pull request #14 from HuiLi/master

合并更新
更新OP_Column
Merge pull request #29 from MinfeiZhou/master

update vdbe.c