v4.0.0

Changes

• make the complete step indicators clickable (#147)
• add a template for the step symbols (#149)
• update to Angular 7 (while retaining compatibility for Angular 5 - 7 projects)
• refactor navigation bar stylesheets (#161)
• improve the barrel export (fixes #131)
• apply the [stepId] of the wizard steps as ids in the navigation bar (#186)
• fix documentation bugs