Add loop example

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

examples/loop.not

@@ -0,0 +1,14 @@
+i = 0;
+while i < 10 {
+    i = i + 1
+    println(i)
+}
+
+i = 0
+loop {
+    if i >= 10 {
+        break
+    }
+    i = i + 1
+    println(i)
+}