RFR: JDK-8268831: Improve javadoc tool handling of streams.

[Jonathan Gibbons]

Please review a relatively simple cleanup left over from last year's cleanup for `JavadocLog` (was `Messager`).

The cleanup here is to rationalize the inconsistent naming and use of methods named `notice` in `JavadocLog` and `ToolEnvironment`, as well as cleanup use of the primitive `Log.printRawLines`. While it would have been nice to move the definition of `ToolEnvironment.notice` into `JavadocLog`  that dragged with it the need for the `quiet` variable, which led to initialization order problems.  The proposed solution is a compromise.

No tests are affected; `noreg-cleanup`.

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

Commit messages:
 - JDK-8268831: Improve javadoc tool handling of streams.

Changes: https://git.openjdk.java.net/jdk/pull/6950/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6950&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268831
  Stats: 69 lines in 5 files changed: 15 ins; 25 del; 29 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6950.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6950/head:pull/6950

PR: https://git.openjdk.java.net/jdk/pull/6950