Pychinko bug: rules that are too trivial don't fire in Pychinko.

Given the file a.n3:
----------------------------
:a :b :c .
{:a :b :c} => {:The :Rule :Fired} .
----------------------------

cwm a.n3 --pythink
does not have the triple ``:The :Rule :Fired''

This bug seems to result from pychinko having some pretty fundemental 
assumptions that an AlphaNode or BetaNode must have at least one 
variable to match.

Yosi