1 去除op_int内建转换机制，修改为隐式（无损，有损）数值转换，并增加float的类似接口
2 修复int和long同值hash不一致的bug
增加文档
Merge pull request #7 from addwork/master

Merge pull request #7 from larva-lang/master
Merge pull request #8 from larva-lang/master

merge