RFR: 8373038: Interpolator factories should follow method naming convention [v2]

[Michael Strauß]

> The following interpolator factories don't follow the standard method naming convention:
> 
> * `Interpolator.SPLINE(double, double, double, double)`
> * `Interpolator.TANGENT(Duration, double, Duration, double)`
> * `Interpolator.TANGENT(Duration, double)`
> * `Interpolator.STEPS(int, StepPosition)`
> 
> New methods named `ofSpline`, `ofTangent`, and `ofSteps` are added. The existing methods are deprecated (not for removal) in favor of the correctly-named methods. This change is in line with the new `ofLinear` method added with #1977.

Michael Strauß 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:

 - doc changes
 - Merge branch 'master' into fixes/interpolator-names
 - Interpolator factories should follow method naming convention

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/1996/files
  - new: https://git.openjdk.org/jfx/pull/1996/files/1fb91b9a..2128f2a9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1996&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1996&range=00-01

  Stats: 999 lines in 23 files changed: 972 ins; 2 del; 25 mod
  Patch: https://git.openjdk.org/jfx/pull/1996.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1996/head:pull/1996

PR: https://git.openjdk.org/jfx/pull/1996