* Lossless image optimization (using ImageOptim).
This shouldn't change the visual appearance of any images. ImageOptim
was run with the highest compression setting except that JPEG metadata
stripping was disabled because some users prefer to avoid stripping
JPEG metadata.
* Update READMEs that have Changelogs for themes impacted by lossless image optmization change.
* Update posts-list.php
Remove reference to theme name because it's breaking the sidebar.
* Update sidebar.php
Fix block errors in the editor.
* Update header.php
Update the column alignment.
