[Matplotlib-devel] Update polar examples?

[OceanWolf]

During my investigation for MEP29 I have noticed in the docs (of 
figure.py) that:
 > (For backward compatibility, ``polar=True`` may also be provided, 
which is equivalent to ``projection='polar'``).

But all the polar examples use ``polar=True``, so perhaps we should 
change the examples to match our current preference (aka 
``projection='polar'``)?  I say perhaps, because I do feel torn about 
this, because I *may* want to change this again with MEP29 assuming it 
gets accepted once I have finished writing it.

I guess I err on updating the examples now because it doesn't hurt, and 
updating them again later if/when we change stuff.

Shall I just make a PR of this now?  Can it still make 1.5?  Would we 
have to backport it, or will it go straight it?

Best,
OceanWolf