Only convert classic microformats classnames if there aren’t microformats2 classnames about php-mf2

[tantek]

While looking at this bug, please also consider:

• http://microformats.org/wiki/microformats2-parsing-issues#uf2_children_on_backcompat_properties
• http://microformats.org/wiki/microformats2-parsing-issues#uf2_children_inside_a_classic_microformats_root_class_name

[tantek]

In particular, as noted in http://microformats.org/wiki/microformats2-parsing#parse_an_element_for_properties :

• parse child elements (document order) by:
• if parsing a backcompat root, parse child element class name(s) for backcompat properties
• else parse a child element class for property class name(s) "p-,u-,dt-,e-"

In particular note that only when parsing a backcompat root, should any backcompat properties be parsed.

[gRegorLove]

Discussion today about only implying properties on mf2 roots, no backcompat roots: https://indiewebcamp.com/irc/2016-05-18#t1463596806212

I can take a stab at some of this.

[aaronpk]

This just got bumped up in my priority list. Since I added hReview markup to my review posts to get them to show up as Google Rich Snippets, the mf2 parsed version of the posts are a total mess. Take a look at this example:

• original post: https://aaronparecki.com/2016/12/15/16/dropvox
• php parsed
• python parsed

It's kind of a giant mess of duplicated objects and values appearing in bizarre places.

[dshanske]

I am for this even if some parsers have an override.