Just show gotoslide field for image and link elements.
Made it easier to add elements that are not separate H5P libraries.
Added internal go-to-slide element. Making it easy to jump between slides.
Less magic numbers when getting props from semantics.
Made code a bit easier to work with.
Fixed slide clone, sort, remove bugs related attachedElements.
Prevent removal of CT form when removing slide.
Merge branch 'go-to-slide' of github.com:h5p/h5p-editor-course-presentation into go-to-slide
Resolve conflicts
Merge branch 'go-to-slide'