initial interface for grcnf_minmean_std using clorefs

This should be working, but I wasn't sure how to correctly abstract expvar. Also, I've added a couple of changes to list.sats that you may or may not want to use as is; I can take a crack at implementing them if you like.


Squashed commits:

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minor changes

makeclo interface working

grcnf_minmean_std typechecks

tidying up a bit

implemented min_first_loop and simplified

complete test of algorithm typechecks but doesn't compile

reorganized a bit

changed expvar to an abstract type, but this isn't quite working