Segfault for some nested aggregate terms in queries

[Joachim Jansen]

Attached is a file that segfaults.

The first query runs properly, the second one "wraps" the first query and requests the nr of answers. This second query results in a segfault

[Bart Bogaerts]

Temporary workaround: replace main with

include <table_utils>
procedure main() {
  print(query(Q1,S))
  print(#totable(query(Q1,S)))
}

[Broes De Cat]

Merged in fix_query_with_aggregates (pull request #235)

Fixes #516, fixes #722, fixes #702: debruiyn index management was incorrect for aggregate kernels.

→ <<cset 99b63fee9b1e>>