Sort autocompletion does not work for asp_structures

[Broes De Cat]

This is important for the ASP competition.

[Broes De Cat]

Turns out to be a much deeper issue with the way structures and asp_structures are parsed: => checking whether domelems of table occur in sort is only checked during autocomplete (wrong) => parsing of structure adds to table directly (not sort checking) => parsing of asp_structure adds to inter (has sort checking)*/

[Broes De Cat]

Fixes #258 by doing sort checks AFTER parsing.

→ <<cset 2e1dbd687e48>>

[Bart Bogaerts]

Fixes #258 by doing sort checks AFTER parsing.

→ <<cset dd535932116c>>