A+-README: Add version notes
A+-README: add sample code at head
A+-README: consolidate Difficulties
A+-README: lower header level
A+-README: improve deferred is-a thenable
A+-README: clarify sequence-point promises
A+-README: add complete example test
A+-README: correct doc for makeSequenceArray
A+-README: add notes about Promises/A+ test
A+-README: misc wording changes
A+-README: minor rewording