If meter, data use element text after content/value attributes

[chaals]

<div itemscope itemtype="http://schema.org/CreativeWork">
<data itemprop="name" value="data value attribute" content="data content attribute" >data element text content</data>
<data itemprop="name" value="lone data value attribute" >missed data element' value attribute [BUG]</data>
<data itemprop="name">data used its element's textContent</data>
<meter itemprop="name" content="meter content attribute" value="meter value attribute">meter element text content</meter>
<meter itemprop="name" value="lone meter value attribute" >missed meter element's value attribute [BUG]</meter>
<meter itemprop="name">meter used its element's textContent</meter>
</div>

in the SDL generates:

data content attribute
meter used its element's textContent
lone meter value attribute
data used its element's textContent
lone data value attribute
meter content attribute

and in Google's SDTT gives

@type: CreativeWork
name: data content attribute
name: missed data element' value attribute [BUG]
name: data used its element's textContent
name: meter content attribute
name: missed meter element's value attribute [BUG]
name: meter used its element's textContent

I'll do more testing, but I think modulo the apparent bug in Google of not reading the value attribute at all, I think we should align the value algorithm to match this behaviour. See also #20, #38