Add Stream.unfold

This generates a possibly finite stream of values.
Make --sup the default for mix

Closes #1706
Merge pull request #1714 from pminten/mix-new-default-sup

Make --sup the default for mix
Merge pull request #1693 from pminten/stream-generate

Add Stream.unfold
Preserve correct order when deps are overriding
Don't compile deps too many times
Merge pull request #1715 from ericmj/mix-deps-order

Preserve correct order when deps are overriding
Get rid of the r helper since it causes conflicts related to modules dependencies
Fix `compile: false` dependency option
Merge pull request #1716 from ericmj/mix-deps-compile-false

Fix `compile: false` dependency option