RFR: JDK-8298405: Support Markdown in Documentation Comments [v31]

[Jonathan Gibbons]

> Please review a patch to add support for Markdown syntax in documentation comments, as described in the associated JEP.
> 
> Notable features:
> 
> * support for `///` documentation comments in `JavaTokenizer`
> * new module `jdk.internal.md` -- a private copy of the `commonmark-java` library
> * updates to `DocCommentParser` to treat `///` comments as Markdown
> * updates to the standard doclet to render Markdown comments in HTML

Jonathan Gibbons has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 40 commits:

 - Merge remote-tracking branch 'upstream/master' into 8298405.doclet-markdown-v3
 - improve support for DocCommentParser.LineKind
 - Merge remote-tracking branch 'upstream/master' into 8298405.doclet-markdown-v3 # Please enter a commit message to explain why this merge is necessary, # especially if it merges an updated upstream into a topic branch. # # Lines starting with '#' will be ignored, and an empty message aborts # the
   commit.
 - update copyright year on test
 - refactor recent new test case in TestMarkdown.java
 - address review feedback
 - address review feedback
 - added test case in TestMarkdown.java for handling of `@deprecated` tag
 - amend comment in test
 - improve comments on negative test case
 - ... and 30 more: https://git.openjdk.org/jdk/compare/2ed889b7...1c64a6e0

-------------

Changes: https://git.openjdk.org/jdk/pull/16388/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16388&range=30
  Stats: 22058 lines in 194 files changed: 21390 ins; 271 del; 397 mod
  Patch: https://git.openjdk.org/jdk/pull/16388.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16388/head:pull/16388

PR: https://git.openjdk.org/jdk/pull/16388