String support and more run-time routines

This is a work in progress.

src/other/test.b

@@ -1,8 +1,9 @@
-/* test.b - test program for B run-time library brt.s
+/* test.b - test program for B run-time library brt.s brtb.b
 
    b test.b test.s
+   b brtb.b brtb.s
    echo abcABC > abc
-   perl as7 --out test.out brt.s test.s bi.s
+   perl as7 --out test.out brt.s brtb.s test.s bi.s
    perl a7out test.out
 */
 
@@ -10,7 +11,8 @@ main {
   extrn fname, fin;
   auto ch;
   
-  fin = open(fname, 0);
+/*  fin = open(fname, 0); */
+  fin = open("abc     ", 0);
 
   goto loop;
   while (ch != 04) {