RFR: JDK-8250766: javadoc adds redundant spaces when @see program element is wrapped [v2]

[Hannes Wallnöfer]

> This changes reference parsing in `DocCommentParser` to normalize whitespace in signatures to a large extent. In particular, multiple whitespace characters are coalesced into a single space character, and whitespace after opening parentheses and angle brackets are suppressed.

Hannes Wallnöfer 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 three additional commits since the last revision:

 - JDK-8250766: Improve signature normalization and move it to CommentHelper
 - Merge branch 'master' into JDK-8250766
 - JDK-8250766: javadoc adds redundant spaces when @see program element is wrapped

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3754/files
  - new: https://git.openjdk.java.net/jdk/pull/3754/files/a64598c2..fa29f553

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3754&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3754&range=00-01

  Stats: 7175 lines in 220 files changed: 4625 ins; 1884 del; 666 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3754.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3754/head:pull/3754

PR: https://git.openjdk.java.net/jdk/pull/3754