Implement sequence number wrapping

For 32-bit integers, overflow occurs at roughly 4 billion, making it a
real problem. This change implements wrapping, allowing for buffer sizes
as large as 2^31.
Remove stray blank lines
README.md: Mention YieldingWaitStrategy in the feature list
README.md: tweak wording of first feature
Print more concise descriptions of wait strategies
BlockingWaitStrategy: Allow callers to specify retry counts