[with patch, positive review] added new combinatorial functions for tableaux and crystals

[aschilling]

I added a two new functions promotion and promotion_inverse for rectangular tableaux.

I also added a reflection operator for the crystal library.

[mhansen]

Hi Anne,

The one thing I would change is that instead of returning the string "Tableaux is not rectangular" is raising a ValueError? with that message. Also, could you add a line before "EXAMPLES" in "def s("?

Other than that, it looks good to go in.

--Mike

[mhansen]

Oh, the doctest for the ValueError? would look something like this:

sage: t = Tableau([[1,2],[2]]) 
sage: t.promotion(3) 
Traceback (most recent call last):
...
ValueError: Tableaux is not recutangular

[aschilling]

fixed the issues that Mike raised

[mabshoff]

Merged promotion_reflection-3418-submitted.patch in Sage 3.0.3.rc0