Add an explicit "is_ghost" property to selected instructions, and use
that to determine whether reload and coloring should visit instructions.
This allows them to visit fallthrough_return instructions and insert
fills and register moves as needed.
* Update to rustfmt-preview.
* Run "cargo fmt --all" with rustfmt 0.4.1.
rustfmt 0.4.1 is the latest release of rustfmt-preview available on the
stable channel.
* Fix a long line that rustfmt 0.4.1 can't handle.
* Remove unneeded commas left behind by rustfmt.