- Improve robustness of blank-master: malformed lists in subsite
parameters could render a subsite useless and hard to correct.
Now the validity of lists is checked, errors are written to the
error.log, invalid parameters are ignored.
- added flat list syntax for ThemeCSS specs (easier to read)
- added parameter ThemeJS similar to ThemeCSS (ability to add head and
body scripts)
- added generalized function template::add_script with non-pos
parameter "-section" which might be "head" or "body" to make both
kind of scripts available to ThemeJS
