tests/test-debugindexdot.out

check-code: Add a ``maxerr`` argument to the ``checkfile`` function

check-code.py used to halt after 15 errors. This changeset adds a new
argument to the checkfile function to control this limit.

created new head
digraph G {
	-1 -> 0
	0 -> 1
	0 -> 2
	2 -> 3
	1 -> 3
}