Only one place need to filter the list of remotes for ignored remotes:
keyPossibilities. Make the full list available to everything else.
This allows getting rid of the special case handing for --from and --to
to make ignored remotes not be ignored with those options.
This takes advantage of the debug logging done by missingh, and I added
my own debug messages for executeFile calls. There are still some other
low-level ways git-annex runs stuff that are not shown by debugging,
but this gets most of it easily.
