Adds clarifications to the documentation in various places. Some notes: * Point 6 should probably be deferred until it is verified that the tutorials are correct enough, seeing as they were updated to Java 8 only. * Point 8 has been deferred until all the animation bugs have been resolevd. * Point 5: I wrote new documentation about the `extractor` for the `observableArrayList(Callback<E, Observable[]> extractor)` method. Later I found that `observableList(List<E> list, Callback<E, Observable[]> extractor)` already talks about it (I updated it too). I'm not sure which of them we want to keep, or maybe merge them. * Point 1: I think that it's necessary to mention the internal implementation behavior even if it requires a caveat that this is only the current behavior and may change in the future. What constitutes a "change" is extremely important and there is no way for the user to know it. I've tripped on this hard when using ReactFX which uses object equality instead, so when the JavaFX observables are wrapped by ReactFX observables, the behavior changes silently. I think that in the future we will want to let the user define what a change is (for example, by creating an overridable method with the current behavior as the default, or using object equality and letting the user override that, although that's more risky). Even a `HashMap` that uses object equality has the sister implementation `IndentityHashMap` to deal with this ambiguity.
------------- Commit messages: - Initial commit of 8228570 Changes: https://git.openjdk.java.net/jfx/pull/276/files Webrev: https://webrevs.openjdk.java.net/jfx/276/webrev.00 Issue: https://bugs.openjdk.java.net/browse/JDK-8228570 Stats: 122 lines in 9 files changed: 60 ins; 13 del; 49 mod Patch: https://git.openjdk.java.net/jfx/pull/276.diff Fetch: git fetch https://git.openjdk.java.net/jfx pull/276/head:pull/276 PR: https://git.openjdk.java.net/jfx/pull/276
