Bumped version to 0.2.0; docs edits.

I've added cond and cmp to the library so that should bump the minor
version no. I think.

docs/Treestep.rst

@@ -1,21 +1,18 @@
 
-Treating Trees II
-=================
+Treating Trees II: ``treestep``
+===============================
 
 Let's consider a tree structure, similar to one described `"Why
 functional programming matters" by John
 Hughes <https://www.cs.kent.ac.uk/people/staff/dat/miranda/whyfp90.pdf>`__,
-that consists of a node value followed by a sequence of zero or more
-child trees. (The asterisk is meant to indicate the `Kleene
+that consists of a node value followed by zero or more child trees. (The
+asterisk is meant to indicate the `Kleene
 star <https://en.wikipedia.org/wiki/Kleene_star>`__.)
 
 ::
 
     tree = [] | [node tree*]
 
-``treestep``
-------------
-
 In the spirit of ``step`` we are going to define a combinator
 ``treestep`` which expects a tree and three additional items: a
 base-case function ``[B]``, and two quoted programs ``[N]`` and ``[C]``.
@@ -591,37 +588,6 @@ To me, that seems simpler than the ``genrec`` version.
     
     ''', D)
 
-.. code:: ipython2
-
-    from joy.library import FunctionWrapper
-    from joy.utils.stack import pushback
-    
-    
-    @FunctionWrapper
-    def cmp_(stack, expression, dictionary):
-        '''
-        cmp takes two values and three quoted programs on the stack and runs
-        one of the three depending on the results of comparing the two values:
-    
-               a b [G] [E] [L] cmp
-            ------------------------- a > b
-                    G
-    
-               a b [G] [E] [L] cmp
-            ------------------------- a = b
-                        E
-    
-               a b [G] [E] [L] cmp
-            ------------------------- a < b
-                            L
-        '''
-        L, (E, (G, (b, (a, stack)))) = stack
-        expression = pushback(G if a > b else L if a < b else E, expression)
-        return stack, expression, dictionary
-    
-    
-    D['cmp'] = cmp_
-
 .. code:: ipython2
 
     J('''\