Adding text about potential flow control deadlock.  Closes #185.
Fixing flow control example. Closes #182.
Adding restriction on PUSH_PROMISE usage.  Closes #175.  Fixes #177.
Clarifying illegal uses of RST_STREAM.  Fixes #176.
Refactoring of priority text for #175.  Adding note about use of PRIORITY for frame transmission prioritization vs. processing prioritization.
Capturing the conclusion of duplicate settings discussion in Berlin.  Closes #174.
Noting magic string exception for version identification rules.  Fixes #173.
Clarifying the use of frames of different types in the reserved states.  Closes #165.
Ensuring the method is shown in uppercase.