支持Mysqli::query(); 完善中文文档

添加中文文档；Skywalking扩展及Agent修改；添加对PHP 7.3.0+的支持

make error: 'for' loop initial declarations are only allowed in C99 mode

error: 'for' loop initial declarations are only allowed in C99 mode
note: use option -std=c99 or -std=gnu99 to compile your code