#2687: add Fishbone-Moncrief disk gallery example to ET

Comment (by Gabriele Bozzola):

I am all for more gallery examples, but I think that the Fishbone-Moncrief thorn should first be fixed (see https://bitbucket.org/einsteintoolkit/tickets/issues/2503/various-small-problems-with). The par file also has lots of commented instructions (some for thorns that are not in the toolkit).

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