Add hello world example

bin/helloworld.wasm

@@ -0,0 +1,26 @@
+# Push "Hello WORLD" onto the stack
+pushi $68;  # D
+pushi $76;  # L
+pushi $82;  # R
+pushi $79;  # O
+pushi $87;  # W
+pushi $32;  # space
+pushi $111; # o
+pushi $108; # l
+pushi $108; # l
+pushi $101; # e
+pushi $72;  # H
+
+seti %B $11; # Length of string on stack
+
+print_loop:
+popi %A;
+int $0;
+
+subi %B $1 %B;
+gti %B $0;
+jmp print_loop;
+
+# Print a newline
+seti %A $10;
+int $0;