Add a command-line flag for separating out embedded structs

[ChimeraCoder]

@AeroNotix and @Skelterjohn point out that in some cases it may be preferable to have distinct named types for struct fields instead of using embedded structs. (See the #go-nuts conversation starting at https://botbot.me/freenode/go-nuts/msg/3067419/)

This wouldn't be too hard to do; the only problem is naming the structs (and avoiding naming collisions). @Skelterjohn outlines one potential method for addressing that here: https://botbot.me/freenode/go-nuts/msg/3067637/ .

[bobbytables]

Is there any way I can help implement this? It's obviously not hard to just separate out with copy/paste but a cmd option would be baller.