cleaning up compose_description_element_text_data()
turning theme function to compose function for Quantitative Data
turning theme function to compose function for CategoricalData
#5583 turning theme function to compose method for IndividualsAssociations
compose metod for IndividualsAssociations and further refactoring
restructuring description element code
removing obsolete palmweb special code
replacing special code for cichorieae feature 'Image source' by generic functionality
renaming functions and code organisation
defined sort order for original sources
fixing problem of image sources not being shown
moving content of folder 7.x up to the repository root