Invalid sourcemap generation

[Toilal]

I think there's an issue with sourcemap generation.

In some case, I'm not able to set breakpoint in some part of the file processed by vue-hot-reload-loader. When I disable this loader, it works properly, so i'm pretty sure the issue comes from this module.

Maybe we could replace AST + estraverse with recast, as it seems to support sourcemap properly through the whole parse + replacement process ...

[ktsn]

@Toilal
Sorry, I don't have enough time to investigate about source map generation of recast now.
If you have confidence that it improves the generated source map, feel free to go ahead.