lib: fix regression in meataxe code that broke grpauto.tst

Also add a new, fast test for SMTX.BasesCSSmallDimUp which
detects that regression much faster than the tests in grpauto.tst

lib/meataxe.gi

@@ -2980,7 +2980,7 @@ local cf,dim,b,den,sub,i,s,q,found,qb;
  qb:=b{[den+1..Length(b)]}; # basis
  qb:=List(s,x->x*qb);
  qb:=Concatenation(b{[1..den]},qb);
- TriangulizeMat(qb);
+ qb:=TriangulizedMat(qb);
  Add(sub,qb);
  s:=SMTX.InducedAction(q,s,3);
  b:=Concatenation(b{[1..den]},s[3]*b{[den+1..Length(b)]});

tst/testinstall/meataxe.tst

@@ -154,5 +154,38 @@ gap> randM := SMTX.RandomIrreducibleSubGModule(M)[2];;
 gap> MTX.IsIrreducible(randM);
 true
 
+#
+# Tests for individual Smash meataxe functions
+#
+
+#
+gap> m:=RegularModule(SymmetricGroup(3), GF(2));
+[ [ (1,2,3), (1,2) ], 
+ rec( IsOverFiniteField := true, dimension := 6, field := GF(2), 
+ generators := [ <an immutable 6x6 matrix over GF2>, 
+ <an immutable 6x6 matrix over GF2> ], isMTXModule := true ) ]
+gap> res:=SMTX.BasesCSSmallDimUp(m[2]);
+[ [ ], [ <a GF2 vector of length 6> ], 
+ [ <a GF2 vector of length 6>, <a GF2 vector of length 6> ], 
+ [ <a GF2 vector of length 6>, <a GF2 vector of length 6>, 
+ <a GF2 vector of length 6>, <a GF2 vector of length 6> ], 
+ [ <a GF2 vector of length 6>, <a GF2 vector of length 6>, 
+ <a GF2 vector of length 6>, <a GF2 vector of length 6>, 
+ <a GF2 vector of length 6>, <a GF2 vector of length 6> ] ]
+gap> Display(Concatenation(res));
+ 1 1 1 1 1 1
+ 1 . . 1 1 .
+ . 1 1 . . 1
+ 1 . . . 1 1
+ . 1 . . 1 .
+ . . 1 . 1 1
+ . . . 1 . 1
+ 1 . . . . .
+ . 1 . . . .
+ . . 1 . . .
+ . . . 1 . .
+ . . . . 1 .
+ . . . . . 1
+
 #
 gap> STOP_TEST("meataxe.tst", 10000);