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

Conflicts:
	xsa/queries.py

new MessageDialogs added (will appear when user has not set user-name, password, host-address or query)

more documentation

trouble with renamed file xsa_skript (renamed to xsa_script)

Conflicts:
	xsa_gui.py
	xsa_script.py

Make files executable

Added shebang and made files executable, to remove the need to launch them with *python $fileame*

Also, renamed xsa_skript to xsa_script.