* More filling out of parent/child unit tests. * Found a bug in the process. Removing a focused child does not reset the parent's activeDescendant state (it was using child.set("focused", false), which is readOnly. Changed to child.blur(). Fixes #2531907

Added No Changes to HISTORY

Updated HISTORY.md files to have unified title headings. Some HISTORY.md files had incorrect title headings, so these changes fix the incorrect ones and unify their format: "[Component] Change History".

Fixed issue where previously rendered children, added to an empty parent, would not get rendered into the parent's child container node. Based on the pull request from andreas-karlsson, with the root fix *and* unit test (nicely done): https://github.com/yui/yui3/pull/25 Fixes #2531093

Added additional check in _uiAddChild, to make sure prev/next sibling is rendered before trying to insert content relative to it. NOTE: This fix is not really required for the out-of-the-box parent/child implementation, but came up because a user had a custom impl. which made child.render() async [probably a valid usecase for parent/child]. See Fixes #2529863

Use extension destructor support, rather than AOP'ing destructor, which won't work. Fixes #2529785

Added 3.4.0 No Changes to HISTORY.mds

Widget-Parent/Position/PositionAlign/PositionConstrain/Stack/StdMod README -> README.md + HISTORY.md