Update README, new tests

tests/function.grnd

@@ -2,5 +2,18 @@ fun !dingus -string
 return "dingle"
 endfun
 
+fun !jumpy
+    set &x 0
+    @loop
+    equal $x 10 &cond
+    if $cond %endloop
+    add 1 $x &x
+    println $x
+    jump %loop
+    @endloop
+endfun
+
 call !dingus &e
 println $e
+
+call !jumpy &x