Version bump to 1.5.4-alpha.
$data is an object, not an array.  Bump featured header to 0.1.1.
Version bump to 1.5.4.
Version bump to 1.5.5-alpha.
Don't unregister the core Recent Posts widget.
Version bump to 1.5.5.
Merge tag '1.5.5' into 1.6

Tagging version 1.5.5.
Update the <time>, <abbr>, and <acronym> styles in the base stylesheets.  Particularly, only use the help (?) cursor if there's a 'title' attribute on the elements.
Add the 'gallery-col-XX' class to the outside container for the gallery to allow for better styling options.
Overhaul the gallery.css file to get rid of some of the specificity and use some newer CSS methods like 'box-sizing'.  Mostly, this should allow theme authors to more easily overwrite some style rules in their themes.