Handling multiple labels #66

In #22, there is a proposal to use labels as "fallback" content for a parameter's description. For example:

<label for=foo>One label</label>
<input id=foo type=text>

could produce a parameter schema like:

{
  "type": "string",
  "description": "One label"
}

That's fine, but an element can have multiple labels attached to it:

<label for=foo>One label</label>
<label for=foo>Another label</label>
<input id=foo type=text>

What do we do then? I have chosen a cave-man approach of joining the texts with ; for now.