CH03::intro: correct Nakamoto facts; clarify Bitcoin Core details

- Previous text said Bitcoin (Core) was "completed" before the Nakamoto
  paper was written, but Nakamoto sent unfinished code to Hal Finney and
  others after the paper was published but prior to the public software
  release, suggesting Bitcoin wasn't completed at that time.  This also
  ignores the two updates (at least) which Nakamoto made to the Bitcoin
  paper after the network was started.  It also seems much more likely
  to me that parts of the code and the paper were written in tandem.

  Update text to say "mostly completed" and "published".

- Drop word "authoritative" from the description of Bitcoin Core as a
  reference implementation.  There's no authority here.

- Change problematic "full network node" language; see edits to previous
  chapters.

ch03.asciidoc

@@ -11,21 +11,20 @@ contributors with about a dozen developers working on the code almost
 full-time and several dozen more on a part-time basis. Anyone can
 contribute to the code—including you!
 
-
 ((("bitcoin whitepaper")))((("Satoshi client")))((("reference
 implementation", see="Bitcoin Core")))((("Bitcoin Core", "reference
 implementation")))When bitcoin was created by Satoshi Nakamoto, the
-software was actually completed before the whitepaper reproduced in
-<<satoshi_whitepaper>> was written. Satoshi wanted to make sure it
-worked before writing about it. That first implementation, then simply
-known as "Bitcoin" or "Satoshi client," has been heavily modified and
+software was mostly completed before the whitepaper reproduced in
+<<satoshi_whitepaper>> was published. Satoshi wanted to make sure it
+worked before publishing about it. That first implementation, then simply
+known as "Bitcoin", has been heavily modified and
 improved. It has evolved into what is known as _Bitcoin Core_, to
-differentiate it from other compatible implementations. Bitcoin Core is
+differentiate it from other implementations. Bitcoin Core is
 the _reference implementation_ of the Bitcoin system, meaning that it is
-the authoritative reference on how each part of the technology should be
+provides a reference for how each part of the technology should be
 implemented. Bitcoin Core implements all aspects of bitcoin, including
-wallets, a transaction and block validation engine, and a full network
-node in the peer-to-peer Bitcoin network.
+wallets, a transaction and block validation engine, and all modern parts
+of Bitcoin peer-to-peer communication.
 
 [WARNING]
 ====