RFR: JDK-8294539: Augment discussion of equivalence relations on floating-point values [v3]

[Joe Darcy]

> While the floating-point == operation is *not* an equivalence relation, there are useful equivalence relations that can be defined over floating-point values. Text is added to java.lang.Double to discuss and name those relations.

Joe Darcy has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:

 - Respond to review feedback.
 - Merge branch 'master' into JDK-8294539
 - Add discussion of numerical equality.
 - Fix typo.
 - JDK-8294539: Augment discussion of equivlance relations on floating-point values

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Changes:
  - all: https://git.openjdk.org/jdk/pull/10498/files
  - new: https://git.openjdk.org/jdk/pull/10498/files/58543643..3a7dfbeb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10498&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10498&range=01-02

  Stats: 8367 lines in 209 files changed: 5462 ins; 2077 del; 828 mod
  Patch: https://git.openjdk.org/jdk/pull/10498.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10498/head:pull/10498

PR: https://git.openjdk.org/jdk/pull/10498