Add tasks for all the new languages

Task/Matrix-multiplication/SequenceL/matrix-multiplication-1.sequencel

@@ -0,0 +1,12 @@
+matmul(A(2), B(2)) [i,j] :=
+        let k := 1...size(B);
+        in  sum( A[i,k] * B[k,j] );
+
+//Example Use
+a := [[1, 2],
+      [3, 4]];
+
+b := [[-3, -8, 3],
+      [-2,  1, 4]];
+
+test := matmul(a, b);

Task/Matrix-multiplication/SequenceL/matrix-multiplication-2.sequencel

@@ -0,0 +1 @@
+matmul(A(2), B(2)) [i,j] := sum( A[i,all] * B[all,j] );