Add runtime test for arrays

This one detects further error cases
that the others didn't (wrong index multiplication under
some circumnstances).

Author: boriel

tests/runtime/arrcheck3.bas

@@ -0,0 +1,19 @@
+
+DIM a(23, 31) as Uinteger
+DIM p as UInteger = @a(0, 0)
+DIM i as Uinteger
+DIM j as UInteger
+DIM m as UInteger
+CLS
+
+FOR i = 0 TO 23
+ FOR j = 0 TO 10
+ LET m = i * 32 + j
+ PRINT i; ","; j; " "; m; " "; @a(i, j); " "; p
+ LET p = p + 2
+ NEXT j
+ STOP
+NEXT i
+
+PRINT INK 4; FLASH 1; " OK "
+