Certain warnings are being treated as errors

[kylef]

I'm not sure what the correct behaviour is here. We are raising some "warnings" in parse results, however these are being treated as errors since the parse result doesn't contain other content.

You can find examples of this in both #252 and #254.

element: "parseResult"
content:
  -
    element: "annotation"
    meta:
      classes:
        - "warning"
    attributes:
      code: 4
      sourceMap:
        -
          element: "sourceMap"
          content: []
    content: "no property name"

The solution is that these warnings should actually be errors, or other content (API name, etc) should be in the parse result.

[kylef]

To reproduce currently:

# API
## Resource [/]
### Action [GET]

+ Response 200 (application/json)
    + Attributes
        + Include Example

## Data Structures
### Example (Other)
### Other

---

element: "parseResult"
content:
  -
    element: "annotation"
    meta:
      classes:
        - "warning"
    attributes:
      code: 1
      sourceMap:
        -
          element: "sourceMap"
          content:
            -
              - 42
              - 32
    content: "Mixin must refer to same type as parent"