RFR: 8290844: Add Skin.install() method [v5]

[Andy Goryachev]

> - added Skin.install()
> - javadoc changes for Skinnable.setSkin(Skin)
> 
> no code changes for Skinnable.setSkin(Skin) yet.

Andy Goryachev 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 16 additional commits since the last revision:

 - 8290844: review comments
 - Merge remote-tracking branch 'origin/master' into 8290844.skin.install
 - 8290844: review comments
 - 8290844: review comments
 - Merge remote-tracking branch 'origin/master' into 8290844.skin.install
 - 8290844: javadoc
 - Merge remote-tracking branch 'origin/master' into 8290844.skin.install
 - 8289397: added space
 - 8290844: skin.install
 - 8290844: whitespace
 - ... and 6 more: https://git.openjdk.org/jfx/compare/04fd1ec9...7d5db78b

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/845/files
  - new: https://git.openjdk.org/jfx/pull/845/files/108efb89..7d5db78b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=845&range=04
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=845&range=03-04

  Stats: 8691 lines in 255 files changed: 5937 ins; 1760 del; 994 mod
  Patch: https://git.openjdk.org/jfx/pull/845.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/845/head:pull/845

PR: https://git.openjdk.org/jfx/pull/845