Split "reset" file into "reset" & "style" files.

- Add a button resets to the "reset" file.
Improve TODOs in the nav component.
Restructure the core imports & improve the comments.
Improve comments in the "style" file.
Split off "experimental" components.
Improve the header and footer components.

- Add test for the header and footer components to the dummy app.
Rename the "access" component "accessibility".
Add headings to the text pages in the dummy app.
Fix "accessibility" component in the generator.
Rename the "nav" component to "navigation".