indent
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experiment: rename 'for' to 'up'

http://arclanguage.org/item?id=18507
clean up layout of math.arc
change up and down to exclude second bound

Makes lib/math.arc *much* cleaner.
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now replace 'loop' with a similar-behaving 'for'
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Periodic pass to make sure all tests in repo pass.
Undid my recent change to ns.arc; might not have been a typo.

One problem: streams.arc uses zck's unit-test repo, which conflicts
with other tests. So we need to run those tests in a separate session.
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all iteration constructs arranged in a streamlined tower
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