simplified navigation in the helper service

mc_frontend/src/app/app.component.html

mc_frontend/src/app/author-detail/author-detail.page.spec.ts

mc_frontend/src/app/author-detail/author-detail.page.ts

mc_frontend/src/app/author/author.page.spec.ts

mc_frontend/src/app/author/author.page.ts

mc_frontend/src/app/doc-exercises/doc-exercises.page.html

mc_frontend/src/app/doc-exercises/doc-exercises.page.ts

mc_frontend/src/app/doc-software/doc-software.page.html

mc_frontend/src/app/doc-voc-unit/doc-voc-unit.page.html

mc_frontend/src/app/doc-voc-unit/doc-voc-unit.page.ts

mc_frontend/src/app/exercise-list/exercise-list.page.spec.ts

mc_frontend/src/app/exercise-list/exercise-list.page.ts

.../app/exercise-parameters/exercise-parameters.page.spec.ts

...d/src/app/exercise-parameters/exercise-parameters.page.ts

mc_frontend/src/app/helper.service.spec.ts

mc_frontend/src/app/helper.service.ts

mc_frontend/src/app/home/home.page.html

mc_frontend/src/app/home/home.page.ts

mc_frontend/src/app/imprint/imprint.page.html

mc_frontend/src/app/imprint/imprint.page.ts