Minor manual cleanup - inlined many format args. This makes the code a bit more readable, and helps spot a few inefficiencies and possible bugs. Note that `&foo` in a `format!` parameter results in a 6% extra performance cost, and does not get inlined by the compiler (yet).
The ToDo list was updated to mark `chcon` as done.
Building and testing `chcon` requires enabling the `feat_selinux` feature. If `make` is used for building, then please specify `SELINUX_ENABLED=1` if building and testing on a system where SELinux is not enabled.