Fixes #153 and #169 and #255

app/controllers/contents/courseware.php

app/views/contents/courseware/courseware.php

app/views/course/courseware/index.php

lib/classes/JsonApi/Routes/Courseware/ContainersCopy.php

...sses/JsonApi/Routes/Courseware/StructuralElementsCopy.php

lib/models/Courseware/BlockTypes/Text.php

resources/assets/stylesheets/scss/courseware.scss

...ue/components/courseware/CoursewareAccordionContainer.vue

...rces/vue/components/courseware/CoursewareActionWidget.vue

resources/vue/components/courseware/CoursewareAudioBlock.vue

...ces/vue/components/courseware/CoursewareCourseManager.vue

...ces/vue/components/courseware/CoursewareImageMapBlock.vue

...ces/vue/components/courseware/CoursewareListContainer.vue

.../vue/components/courseware/CoursewareManagerContainer.vue

...es/vue/components/courseware/CoursewareManagerElement.vue

...vue/components/courseware/CoursewareStructuralElement.vue

...ces/vue/components/courseware/CoursewareTabsContainer.vue

resources/vue/courseware-index-app.js

resources/vue/mixins/courseware/export.js

resources/vue/mixins/courseware/import.js