Reworked the example. Avoiding the AtlasGroup command makes it much h…

…arder

as SU gives a group on >>325 points. Also construct the subgroup directly to avoid homomorphism
search.

tst/testbugfix/2018-05-24-IntermediateSubgroups.tst

@@ -1,11 +1,21 @@
 # test for MaximalSubgroupClassReps with options (reported through
 # observation by S.Alavi with IntermediateGroup
+# More complicated to construct w/o AtlasSubgroup to ensure the 325 points action, as it is too
+# slow otherwise. Also construct the smaller subgroup s1 directly.
+# Finally do not slow down with assertions that don't need testing here
 
-gap> g:= SU(IsPermGroup,4,4);;  Size( g );
+gap> SetAssertionLevel(0);;
+gap> g:=SU(IsPermGroup,4,4);;
+gap> sy:=SylowSubgroup(g,2);;
+gap> n:=Filtered(NormalSubgroups(sy),x->IsAbelian(x) and Size(x)=256);;
+gap> sub:=Normalizer(g,n[1]);;
+gap> g:=Action(g,RightTransversal(g,sub),OnRight);;
+gap> NrMovedPoints(g);Size(g);
+325
 1018368000
-gap> h:= Image( IsomorphismPermGroup( PSL(2,16) ) );;
-gap> l:=IsomorphicSubgroups(g,h);;
-gap> s1:= Image( l[1] );;  Size( s1 );
+gap> s:=Stabilizer(g,1);;
+gap> s1:=Complementclasses(s,RadicalGroup(s));;
+gap> s1:=s1[1];;Size(s1);
 4080
 gap> n1:= Normalizer( g, s1 );;  Size( n1 );
 24480