(Issue 839: expose breakpoint variables in wizard)

Add wizard settings for the viewport size in ems
triggering change to mobile view or medium screen view
Some changes to description of option, add notes.
Wizard settings for TR and most  non-child styles.
Remove preset defaults.
Remove redundant  wizard options for Blanket.
Fix tabs style.
Merge pull request #867 from LivredOr/438_wizard_breakpoints

(Issue 839: expose breakpoint variables in wizard)