Begun to work through recording seller-vendor-etc consensus.
Allowing Integer values for a 'position'.
These have been observed in the wild, and can also be
supplied via sub-properties such as episodeNumber. Note that
RDFa and JSON-LD allow explicit datatyping syntax if needed.
Seller/vendor fixes, towards https://github.com/rvguha/schemaorg/issues/88
See https://www.w3.org/wiki/images/7/7e/ProviderSellerVocabularyRe-DesignProposal.pdf
Draft implementation detail overview: https://www.w3.org/wiki/WebSchemas/SellerVendorCleanup#Implementation_Details

This needs checking and domains for 'broker' confirming. Also examples.txt will need updates.
Merge branch 'master' into sdo-sellerbroker

Conflicts:
	data/schema.rdfa
'broker' property is expected on the Order type.
per-property pages show any superceded properties.
Fixed backwards-worded comment on supercedes().
TODO: add similar to the superceded property's page. That
is slightly harder to look up.
Adding 'supercedes', 'supercededBy' to per-property page.
TODO: currently the entry e.g. for 'seller' in
http://schema.org/Offer won't list multiple properties that it
replaces. Fixing that (existing) bug will need a minor API change
since supercedes() only returns the first superceded property. The
only case of that is in the sdo-sellerbroker branch, so we'll come
to that afterwards.
Merge branch 'master' into sdo-sellerbroker
Improved display of supercededBy information.
Previous code assumed a property superceded only one other.
Added supercedes_all to the API, and use it in per-type and
per-property pages. Should add caching in future, but the HTML
is cached so proceeding as-is for now.
seller is a suproperty of participant (esp. as we replace 'vendor')
Noted "and flights" re carrier. Added seller to Flight.
Added "Use 'provider' to represent carrier" to Flight.
Updated example to use 'provider' instead of 'carrier'.
Merge pull request #89 from danbri/sdo-sellerbroker

Fixes around seller, broker, merchant vocabulary to reduce variation and confusing.

Addresses https://github.com/rvguha/schemaorg/issues/88 - see issue tracker for backstory.
read_file() now explicitly unicode, as is api.py itself.
Replaced some chars that caused unicode issues, added BibEx.
Replaced comma-like and semicolon-like unicode with basic ascii.
Python was failing to encode
http://www.fileformat.info/info/unicode/char/37e/browsertest.htm
and http://www.fileformat.info/info/unicode/char/2019/browsertest.htm

In addition to switching read_file to explicitly use unicode, the
input files are currently stripped of these non-ascii chars.
Added note requesting utf-8 and basic file format info.
Merge pull request #90 from danbri/master

Fixes charset/encoding issues
Updated Flight/FlightReservation example, for seller + flightNumber changes.
Merge pull request #91 from danbri/master

Updated Flight/FlightReservation example w/ seller + flightNumber changes