- Makes .entry-content 100% wide to let the box-model work determine .alignfull widths
- .alignwide and default widths now have a fixed width, and a responsive 100% max-width
- Updates utility classes to work with this change
- Improves nested block behaviors and reduces CSS load
- Removes .responsive-max-width utility classes from .entry-content and simialr wrappers that no longer need it
- Renames responsive @extends and @mixins to match Gutenberg pre/suffixes
