#8 order of printed cards

[Joachim Gabler]

The order of cards in a printout has two bugs:

1. sub strings are sorted after longer strings, e.g. a
main heading without sub heading is sorted after the
same main heading with a sub heading.

2. Catalogue cards with headings are not sorted correctly:
The order is set as either the heading or as author +
title
(heading | [author] + title).
It should be [heading] + [author] + title