RFR: 8237491: Maximized undecorated stage behaves inconsistently on different platforms (fix for Linux)

[Thiago Milczarek Sayao]

Simple fix to enable maximizing functionality on the window manager.

Test provided
 gradlew -PFULL_TEST=true -PUSE_ROBOT=true :systemTests:test --tests test.javafx.stage.MaximizeUndecorated

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

Commit messages:
 - Change copyright year
 - Enable maximize functionality when maximizing
 - Merge pull request #13 from openjdk/master
 - Merge pull request #12 from openjdk/master
 - Merge pull request #11 from openjdk/master
 - Merge pull request #10 from openjdk/master
 - Merge pull request #9 from openjdk/master
 - Merge pull request #8 from openjdk/master
 - Merge pull request #7 from openjdk/master
 - Merge pull request #6 from openjdk/master
 - ... and 2 more: https://git.openjdk.java.net/jfx/compare/cb545cc6...821e9ad2

Changes: https://git.openjdk.java.net/jfx/pull/345/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=345&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8237491
  Stats: 96 lines in 2 files changed: 96 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/345.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/345/head:pull/345

PR: https://git.openjdk.java.net/jfx/pull/345