This fixes a bug in which the validity of FROM_DIR and TO_DIR were
checked before ~ and relative paths in those arguments were expanded,
sometimes this could cause dotfilemanager to complain that a valid path
was invalid. Expand the paths and _then_ check their validity.
You can now just do `dotfilemanager tidy` (with no further arguments) to
tidy up symlinks in your homedir, and `dotfilemanager report` or
`dotfilemanager link` to report on or make links from ~ into
~/.dotfiles.
Fix bug with relative paths: always convert paths retrieved from the
command line args or from reading a link to absolute paths and expand
~'s.
Silence some print statements unless doing the report action.
Delete an unnecessary `path = os.path.join(to_dir,filename)` line.
