Action messages fiddling
Fixed variable setup on Fish shell
Fixing environment updates
Consistently print one item per line in --short mode

closes #1838
Cleanup status line printing
Fixed 'opam install --deps-only'
Causes: avoid the so-often off '[upstream changes]'

We can't assume when we don't know the direct cause: better to display nothing.
Improved signal handling (and windows compat)
Improved some messages
Merge pull request #1882 from OCamlPro/fixes

Various fixes