added neg and bitnot to the stdlib and made a fib.sl example

fib.sl

@@ -0,0 +1,16 @@
+import stdlib/stdlib.sl
+import stdlib/io.sl
+
+: main
+    1 1 2dup 2dup puti cr puti cr
+    +
+    dup puti cr
+    rot
+    22 dup >r for
+        2dup + dup puti cr
+        rot
+    next
+    "-------" puts
+    r> 3 + puti
+    " numbers printed from the fibonaci sequence" puts
+;