allow complete overriding of names of nested fields

[mschoch]

Right now if you have:

{
Names: {
Text: "abc"
}
}

You might want to make the field searchable as just "name". But, currently you can only override it to be "Names.". You should be able to override the whole path if you choose.

[pdf]

This is definitely desirable, for example, when indexing embedded structs.