Feature request: Cobertura -> Jacoco

[colindean]

As described in craigatk/projektor#360, I've got a setup that is emitting Cobertura XML and a destination for the data that requires Jacoco XML. cover2cover seems to have contained some of this knowledge but there's not much AST modeling going on, just an element-wise transfer.

It'd be cool if cover2cover could convert these formats to each other, even if it might be lossy.