Merge pull request #1 from HuiLi/master

合并老师的更新
Merge pull request #2 from HuiLi/master

合并更新
Merge pull request #3 from HuiLi/master

合并更新
Merge pull request #4 from HuiLi/master

合并更新
5段vdbe.c的文档说明

对5段还没有翻译的vdbe.c的文档说明进行了翻译
Merge pull request #17 from MinfeiZhou/master

5段vdbe.c的文档说明