signals for dis-/enabling Download- and Comparison-Button deleted. Methods in question will be called when query was send

signal added, which emits after testing rest-string. if not set, the download button will be disabled

queries.py - contains methods for downloading and searching
datatypereader.py - contains methods for readen datatype and their fields from json files
xsa_skript.py -  skript for starting xsa without a gui