Allow indentation to manage which data a tag is adding to.

Currently, it's hard or impossible to add @return to a @option that is part of a @param like:

```
@function
@param {Object} options
@option {function(String)} name(newName)
@return {Boolean} true if successful.
```

It's impossible to know if the `@return` belongs to the outer function or the `@option` function.

Instead, if tags understood indentation ...

```
@function
@param {Object} options
@option {function(String)} name(newName)
@return {Boolean} true if successful.
```

The `@option` would be added to the `@param` Object, and `@return` to the @option's function.

I'm thinking of making it work by having any indentation of a `@tag` gets called with the "prev" data.

Ideally if descriptions were also indented like:

```
@function
@param {Object} options
param description

@option {function(String)} name(newName)
option description

@return {Boolean} true if successful.
return description

body
```

this could avoid needing a @body tag.