if an item has multiple URL values, return the one that is on the same domain

Treats `https://example.com` and `https://example.com/` as equivalent when comparing URLs. Closes #33

closes #32

uses the video's poster frame as the photo if any of the multi-post images are videos

checkin data is returned embedded like author data rather than in the `refs` object

closes #35

closes #40

thanks to the new backcompat in php-mf2 0.3.2

closes #20

skip image alt text for now

closes #34

closes #36

they are part of the reposted object instead.

closes #27

closes #24

* closes #23
* major refactor of the methods for extracting properties to consolidate the logic
* hReview parsing is incomplete due to issues with the php-mf2 backcompat parsing. see https://github.com/indieweb/php-mf2/issues/107

closes #16

* closes #14
* updated readme with details of the response
* includes `url` and `code` in the response with the final URL after following redirects and the HTTP status code returned

apparently some people's profile URLs don't get t.co'd

:headdesk:

closes #18

If the input URL contains a fragment, finds the DOM tree at that ID and runs the subtree through the mf2 parser.

closes #15

* fields that should be URLs will now be omitted if the value was not a URL, such as when the value is `javascript:alert()`
* makes Mf2 class slightly more self-contained by duplicating the URL helper functions into it
* fixes tests to not cache responses in memcache

closes #9

use fork of php-mf2 until https://github.com/indieweb/php-mf2/pull/83 is merged

see http://microformats.org/wiki/microformats2-parsing-issues#ignore_u-camelCase_properties for background

allow only a basic set of tags, and remove any non-mf2 classes

closes #2

sanitize the HTML returned in the content property. allows a common set of HTML tags.

for #2